Digital television transmitting system and receiving system and method of processing broadcast data

ABSTRACT

A DTV transmitting system includes a frame encoder, a randomizer, a block processor, a group formatter, a deinterleaver, and a packet formatter. The frame encoder builds an enhanced data frame and adds parity data into the data frame. The frame encoder further divides the data frame into first and second sub-frames including first and second portions of the parity data, respectively, and permutes a plurality of the first sub-frames and a plurality of the second sub-frames, respectively. The randomizer randomizes enhanced data in the permuted sub-frames, and the block processor codes the randomized data at a rate of 1/N1. The group formatter forms a group of enhanced data having one or more data regions and inserts the 1/N1 coded data into at least one of the data regions. The deinterleaver deinterleaves the group of enhanced data, and the packet formatter formats the deinterleaved data into enhanced data packets.

This application claims the benefit of earlier filing date and right ofpriority to Korean Patent Application No. 10-2006-0046303, filed on May23, 2006, and Korean Patent Application No. 10-2006-0089736, filed onSep. 15, 2006, and also claims the benefit of U.S. ProvisionalApplication No. 60/883,998, filed on Jan. 8, 2007, the contents of allof which are hereby incorporated by reference herein in theirentireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to digital television (DTV) systems andmethods of processing broadcast data.

2. Discussion of the Related Art

Presently, the technology for processing digital signals is beingdeveloped at a vast rate, and, as a larger number of the population usesthe Internet, digital electric appliances, computers, and the Internetare being integrated. Therefore, in order to meet with the variousrequirements of the users, a system that can transmit diversesupplemental information in addition to video/audio data through adigital television channel needs to be developed.

Some users may assume that supplemental data broadcasting would beapplied by using a PC card or a portable device having a simple in-doorantenna attached thereto. However, when used indoors, the intensity ofthe signals may decrease due to a blockage caused by the walls ordisturbance caused by approaching or proximate mobile objects.Accordingly, the quality of the received digital signals may bedeteriorated due to a ghost effect and noise caused by reflected waves.However, unlike the general video/audio data, when transmitting thesupplemental data, the data that is to be transmitted should have a lowerror ratio. More specifically, in case of the video/audio data, errorsthat are not perceived or acknowledged through the eyes or ears of theuser can be ignored, since they do not cause any or much trouble.Conversely, in case of the supplemental data (e.g., program executionfile, stock information, etc.), an error even in a single bit may causea serious problem. Therefore, a system highly resistant to ghost effectsand noise is required to be developed.

The supplemental data are generally transmitted by a time-divisionmethod through the same channel as the video/audio data. However, withthe advent of digital broadcasting, digital television receiving systemsthat receive only video/audio data are already supplied to the market.Therefore, the supplemental data that are transmitted through the samechannel as the video/audio data should not influence the conventionalreceiving systems that are provided in the market. In other words, thismay be defined as the compatibility of broadcast system, and thesupplemental data broadcast system should be compatible with thebroadcast system. Herein, the supplemental data may also be referred toas enhanced data. Furthermore, in a poor channel environment, thereceiving performance of the conventional receiving system may bedeteriorated. More specifically, resistance to changes in channels andnoise is more highly required when using portable and/or mobilereceivers.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a digital television(DTV) transmitting system and a DTV receiving system and a method ofprocessing broadcast data that substantially obviate one or moreproblems due to limitations and disadvantages of the related art.

An object of the present invention is to provide a DTV transmittingsystem and a DTV receiving system and a method of processing broadcastdata that is suitable for transmitting supplemental data and that ishighly resistant to noise.

Another object of the present invention is to provide a DTV transmittingsystem and a DTV receiving system and a method of processing broadcastdata that can perform additional encoding on enhanced data andtransmitting the processed enhanced data, thereby enhancing theperformance of the receiving system.

A further object of the present invention is to provide a DTVtransmitting system and a DTV receiving system and a method ofprocessing broadcast data that can multiplex known data that are alreadyknown by a receiving system and/or a transmitting system and enhanceddata with main data, and transmit the multiplexed data, therebyenhancing the performance of the receiving system.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, adigital television (DTV) transmitting system includes a frame encoder, arandomizer, a block processor, a group formatter, a deinterleaver, and apacket formatter. The frame encoder builds an enhanced data frame andencodes the enhanced data frame for error correction by adding paritydata. The frame encoder further divides the encoded data frame intofirst and second sub-frames including first and second portions of theparity data, respectively. The frame then permutes a plurality of thefirst sub-frames and a plurality of the second sub-frames, respectively.The randomizer randomizes enhanced data in the permuted sub-frames, andthe block processor codes the randomized enhanced data at an effectivecoding rate of 1/N1. The group formatter forms a group of enhanced datahaving one or more data regions and inserts the enhance data coded atthe effective coding rate of 1/N1 into at least one of the data regions.The deinterleaver deinterleaves the group of enhanced data, and thepacket formatter formats the deinterleaved data into enhanced datapackets.

In another aspect of the present invention, a digital television (DTV)receiving system includes a tuner, a demodulator, an equalizer, a blockdecoder, a data formatter, and a frame decoder. The tuner receives adigital broadcast signal including main and enhanced data. Thedemodulator demodulates the digital broadcast signal, and the equalizercompensates channel distortion of the demodulated signal. The blockdecoder decodes each block of enhanced data in the channel-equalizedsignal. The data deformatter deformats the decoded enhanced data andderandomizes the deformatted enhanced data. The frame decoder forms agroup of first sub-frames and a group of second sub-frames and performsreverse permutation on the group of first sub-frames and the group ofsecond sub-frames, respectively. Each first sub-frame includes thederandomized enhanced data and first parity data, and each secondsub-frame includes second parity data. The frame decoder further formsan enhanced data frame by combining the first and second sub-frames anddecodes the enhanced data frame for error correction.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiments of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 illustrates a general diagram of a digital broadcast transmittingsystem according to the present invention;

FIG. 2( a) to FIG. 2( e) illustrate examples showing the steps of anerror correction encoding process according to a first embodiment of thepresent invention;

FIG. 3 and FIG. 4 illustrate examples show the step of a row permutationprocess according to the first embodiment of the present invention;

FIG. 5( a) to FIG. 5( c) illustrate examples showing the steps of anerror detection encoding process according to an embodiment of thepresent invention;

FIG. 6( a) and FIG. 6( b) illustrate examples of dividing an encodedframe into a plurality of sub-frames according to the first embodimentof the present invention;

FIG. 7( a) to FIG. 7( e) illustrate examples showing the steps of anerror correction encoding process according to a second embodiment ofthe present invention;

FIG. 8 and FIG. 9 illustrate examples show the step of a row permutationprocess according to the second embodiment of the present invention;

FIG. 10( a) and FIG. 10( b) illustrate examples of dividing an encodedframe into a plurality of sub-frames according to the second embodimentof the present invention;

FIG. 11 illustrates a block diagram showing the structure of a digitalbroadcast transmitting system according to an embodiment of the presentinvention;

FIG. 12 illustrates a block diagram showing the structure of a digitalbroadcast transmitting system according to another embodiment of thepresent invention;

FIG. 13 illustrates a block diagram showing the structure of a digitalbroadcast transmitting system according to yet another embodiment of thepresent invention;

FIG. 14 and FIG. 15 illustrate examples of data configuration prior toand after a data deinterleaver in a digital broadcast transmittingsystem according to the present invention;

FIG. 16 illustrates a block diagram showing a demodulator within adigital broadcast receiving system according to an embodiment of thepresent invention;

FIG. 17 illustrates a flow chart showing the general steps of an errorcorrection decoding process according to a third embodiment of thepresent invention;

FIG. 18 illustrates a detailed diagram showing the steps of combiningfirst and second sub-frames and performing the error correction encodingprocess of FIG. 17;

FIG. 19 illustrates a flow chart showing the general steps of an errorcorrection decoding process according to a fourth embodiment of thepresent invention;

FIG. 20 illustrates a block diagram showing the structure of a digitalbroadcast transmitting system according to yet another embodiment of thepresent invention;

FIG. 21 and FIG. 22 illustrate another examples of data configuration atbefore and after ends of a data deinterleaver in a transmitting systemaccording to the present invention;

FIG. 23 illustrates a block diagram showing a general structure of ademodulating unit within a digital broadcast (or television or DTV)receiving system according to another embodiment of the presentinvention;

FIG. 24 illustrates a block diagram showing the structure of a digitalbroadcast (or television or DTV) receiving system according to anembodiment of the present invention; and

FIG. 25 illustrates a block diagram showing the structure of a digitalbroadcast (or television or DTV) receiving system according to anotherembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts. In addition,although the terms used in the present invention are selected fromgenerally known and used terms, some of the terms mentioned in thedescription of the present invention have been selected by the applicantat his or her discretion, the detailed meanings of which are describedin relevant parts of the description herein. Furthermore, it is requiredthat the present invention is understood, not simply by the actual termsused but by the meaning of each term lying within.

In the present invention, the enhanced data may either consist of dataincluding information such as program execution files, stockinformation, weather forecast, and so on, or consist of video/audiodata. Additionally, the known data refer to data already known basedupon a pre-determined agreement between the transmitting system and thereceiving system. Furthermore, the main data consist of data that can bereceived from the conventional receiving system, wherein the main datainclude video/audio data. By performing additional encoding on theenhanced data and by transmitting the processed data, the presentinvention may provide robustness to the enhanced data, thereby enablingthe data to respond more effectively to the channel environment thatundergoes frequent changes. For example, the present invention mayperform each of an error correction encoding process, an error detectionencoding process, and a row permutation process at least once on theenhanced data.

FIG. 1 illustrates a block diagram showing a unit of a digital broadcasttransmitting system for performing the error correction encoding processaccording to the present invention. The unit includes a RS frame encoder101, a data processor 102, and a packet multiplexer 103. In theabove-described structure of the present invention, the main data areinputted to the packet multiplexer 103, and the enhanced data areinputted to the RS frame encoder 101. Herein, additional encodingprocesses are performed on the enhanced data, thereby providingrobustness to the enhanced data, so that the enhanced data can respondeffectively and instantly to the noise and change in channel. The RSframe encoder 101 receives the enhanced data and configures frames forthe additional encoding processes. Encoding processes such as the errorcorrection encoding process, the error detection encoding process, andthe row permutation process are performed on the configured frames,which are then outputted to the data processor 102. The encodingprocesses will be described in more detail in a later process.

The data processor 102 processes the enhanced data that are outputtedfrom the RS frame encoder 101 with a data randomizing, data expansion,data group configuration, and data deinterleaving. Thereafter, theprocessed data are outputted to the packet multiplexer 103 in a MPEG TSpacket format (i.e., enhanced data packets) of 188-byte units. Morespecifically, as one of the processes performed by the data processor102, the data processor 102 configures data groups divided into aplurality of hierarchical areas (or layers). Then, by taking thecharacteristics of the hierarchically divided areas and thecharacteristics of the enhanced data, the enhanced data are insertedinto each of the hierarchically divided areas within the data group.

In the example set forth in the description of the present invention,with respect to the data configuration prior to the data deinterleavingprocess, the data group may be divided into 3 hierarchical areas: a headarea, a body area, and a tail area. More specifically, based on the datagroup being data-interleaved and outputted, the portion being outputtedfirst corresponds to the head area, the portion being outputted nextcorresponds to the body area, and the portion being outputted lastcorresponds to the tail area. At this point, with respect to the datagroup being that is inputted for data deinterleaving, data may beallocated to each the head, body, and tail areas of the data group sothat the body area is entirely configured of the enhanced data, therebypreventing the enhanced data from being mixed with the main data in thebody area.

The data group is divided into 3 different areas so that each area mayfunction and be used differently. More specifically, the body area isallocated with enhanced data only so as to prevent any interference withthe main data from occurring, thereby enabling more robust and effectivereceiving performance. On the other hand, in the head and tail areas,the enhanced data are mixed with the main data in accordance with theoutput order of the data from the interleaver. Thus, the receivingperformance of the head and tail areas may be deteriorated as comparedto that of the body area. Further, if a system inserting known data inthe data group and outputting the known data inserted data group isused, and when a consecutively long set of known data is to beperiodically inserted in the enhanced data, such known data may beinserted in the body area where the enhanced data are not mixed with themain data.

In other words, known data having a constant pre-determined length maybe periodically inserted in the body area. However, it is difficult toperiodically insert such known data having a constant pre-determinedlength in the head area and/or the tail area. It is also difficult toinsert data having a consecutively long length. Meanwhile, the packetmultiplexer 103 multiplexes the inputted enhanced data packet and maindata packet in accordance with a pre-defined multiplexing method. Themultiplexed data packets are then outputted. Hereinafter, the encodingprocesses of the RS frame encoder 101 will now be described in detail.The encoding processes performed on the enhanced data will be describedin detail according to first and second embodiment of the presentinvention.

First Embodiment

According to a first embodiment of the present invention, the RS frameencoder 101 performs a primary error correction encoding process on thereceived enhanced data in a column direction. Thereafter, the RS frameencoder 101 performs a secondary error correction encoding process onthe primarily error correction encoded enhanced data in a row direction,thereby providing robustness to the enhanced data. At this point, thepresent invention may also perform the primary error correction encodingprocess in a row direction, and perform the secondary error correctionencoding process in a column direction. Furthermore, the presentinvention may also sequentially perform a row permutation process and anerror detection process on processed enhanced data. Herein, the rowpermutation process consists of permuting enhanced data in equal sizesso as to scatter group error that may occur during changes in afrequency environment, thereby enabling the enhanced data to respond tothe frequency environment, which is extremely vulnerable and liable tofrequent changes.

FIG. 2( a) to FIG. 2( e) illustrate examples showing the steps of anerror correction encoding process according to a first embodiment of thepresent invention. In this embodiment, the inputted enhanced data aredivided into units of an equal length A. A plurality of A-lengthenhanced data units is grouped to configure a RS frame. Then, a primaryerror correction encoding process is performed on the configured framein a column direction, thereby adding parity data to the primarily errorcorrection encoded enhanced data in a column direction. Subsequently, asecondary error correction encoding process is performed in a columndirection on the enhanced data having parity data added thereto in a rowdirection, thereby adding parity data to the secondarily errorcorrection encoded enhanced data in a row direction.

In the present invention, the particular length A will be referred to asthe row for simplicity. Herein, the value A will be decided by thesystem designer. Additionally, in this example, the error correctionencoding process adopts the RS encoding process. For example, if theinputted enhanced data correspond to a MPEG transport stream (TS) packetconfigured of 188-byte units, the first MPEG synchronization byte isremoved, as shown in FIG. 2( a), thereby configuring a 187-byte row A,as shown in FIG. 2( b). Herein, the first MPEG synchronization byte isremoved because each of enhanced data packets has the same value if afixed byte that can be removed is not included in the inputted enhanceddata, or if the length of the inputted packet is not 187 bytes, theinput data are divided into 187-byte units, thereby configuring a row Adivided into 187 bytes. In a row A is decided in accordance with theabove-described process, a plurality of rows (A's) is grouped to form aRS frame. As shown in FIG. 2( c), in the first embodiment of the presentinvention, 67 rows are grouped to form a single RS frame.

A (Nc,Kc)-RS encoding process is performed on each column in the RSframe so as to generate Nc−Kc number of parity bytes. Then, thegenerated Nc−Kc number of parity bytes are added at the end portion ofeach corresponding column (i.e., after the 67^(th) row of eachcorresponding column) In this example, Nc is equal to 85, and Kc isequal to 67 (i.e., Nc=85 and Kc=67). Accordingly, the parity data beingadded to each column, as shown in FIG. 2( d), correspond to 18 bytes.When the (85,67)-RS encoding process is performed on each of the 187columns within the RS frame, a RS frame includes 187 bytes in each rowand 85 bytes in each column. In other words, the RS frame configured asa result of the primary error correction encoding process includes 85rows each configured of 187 bytes.

Subsequently, a (Nr,Kr)-RS encoding process is performed on each row inthe RS frame, which is RS-encoded in a column direction as shown in FIG.2( d), so as to generate Nr−Kr number of parity bytes. Then, thegenerated Nr−Kr number of parity bytes are added at the end portion ofeach corresponding row (i.e., after the 187^(th) column of eachcorresponding row). In this example, Nr is equal to 201, and Kr is equalto 187 (i.e., Nr=201 and Kr=187). Accordingly, the parity data beingadded to each row, as shown in FIG. 2( e), correspond to 14 bytes. Whenthe (201,187)-RS encoding process is performed on each of the 85 rowswithin the RS frame, a RS frame includes 201 bytes in each row and 85bytes in each column. In other words, the RS frame configured as aresult of the secondary error correction encoding process includes 85rows each configured of 201 bytes.

As described above, according to the first embodiment of the presentinvention, since the number of bytes configuring each row, the number ofrows configuring the RS frame, and the values of Nr, Nc, Kr, and Kc,which are used for the RS encoding process may vary depending upon thesystem design and any other circumstances, these details are not limitedonly to the examples given in the first embodiment of the presentinvention. Meanwhile, a row permutation process may be performed on theprimarily and secondarily RS encoded enhanced data, as described above.Herein, by performing the row permutation, group errors that may occurduring changes in a frequency environment may be scattered, therebyenabling the enhanced data to respond to the frequency environment,which is extremely vulnerable and liable to frequent changes.

More specifically, in the present invention, the secondarily errorcorrection encoded RS frame (i.e., the RS frame having 85 rows eachconfigured of 201 bytes) is divided into 2 RS sub-frames. For example,the enhanced data that are inputted to the RS frame encoder 101 for theRS encoding process (i.e., payload data) and the parity data that aregenerated by an RS encoding process performed in a column direction arecollectively referred to as a “first RS sub-frame”. The parity data thatare generated by an RS encoding process performed in a row direction arereferred to as a “second RS sub-frame”. Therefore, the first RSsub-frame includes 85 units of 187 bytes, and the second RS sub-frameincludes 85 units of 14 bytes. Accordingly, a row permutation process isperformed on each of the above-described first RS sub-frame and secondRS sub-frame.

FIG. 3 illustrates a row permutation process performed on the first RSsub-frame, and FIG. 4 illustrates a row permutation process performed onthe second RS sub-frame. Referring to FIG. 3, when a first RS sub-frameincluding 187 bytes in each row and 85 bytes in each column isconfigured, G number of first RS sub-frames are grouped to configure afirst RS sub-frame group consisting of 85*G number of 187-byte rows.When the row permutation process is performed on the above-describedfirst RS sub-frame group by using a predetermined method, the positionof the rows may differ prior to and after the row permutation processwithin the first RS sub-frame group, as shown in FIG. 3. Morespecifically, the i^(th) row of the first RS sub-frame group prior tothe row permutation process is positioned in the j^(th) row of the samefirst RS sub-frame after row permutation. The above-described relationbetween i and j can be easily understood with reference to Equation 1below.j=G(i mod 85)+└i/85┘i=85(j mod G)+└j/G┘  Equation 1

where 0≦i, j<85G

Herein, each row of the RS frame group is configured of 195 bytes evenafter being processes with row permutation.

Meanwhile, referring to FIG. 4, when a second RS sub-frame including 14bytes in each row and 85 bytes in each column is configured, G number ofsecond RS sub-frames are grouped to configure a second RS sub-framegroup consisting of 85*G number of 14-byte rows. When the rowpermutation process is performed on the above-described second RSsub-frame group by using a predetermined method, the position of therows may differ prior to and after the row permutation process withinthe second RS sub-frame group, as shown in FIG. 4. More specifically,the i^(th) row of the second RS sub-frame group prior to the rowpermutation process is positioned in the j^(th) row of the same secondRS sub-frame after row permutation. Similarly, each row of the second RSsub-frame group is configured of 14 bytes even after the row permutationprocess is performed. The above-described relation between i and j ofthe second RS sub-frame group may be applied to the above-describedEquation 1, or another row permutation method may be applied herein.

In other words, Equation 1 corresponds to a row permutation methodaccording to the first embodiment of the present invention. Any rowpermutation method in which i and j may include all rows within theframe group may be used. The permutation method is not limited only tothe examples given in the description of the present invention.Furthermore, in using the equation for performing row permutation on thefirst and second RS sub-frames, the same equation may be used on bothsub-frames, or a different equation may be used on each sub-frame.

In addition, an error detection encoding process may be performed on thefirst RS sub-frame group that is processed with row permutation. Theerror detection encoding process is used for indicating whether the dataof the first RS sub-frame group have been damaged by any error that mayoccur while the data are being transmitted to the receiving systemthrough the channels. For example, CRC encoding may be used in the errordetection encoding process. Alternatively, any error detection encodingmethod other than the CRC encoding method may also be used. Furthermore,an error correction encoding method may be used to enhance the overallerror correction performance of the receiving system.

FIG. 5( a) to FIG. 5( c) illustrates examples of the CRC encodingprocess according to the present invention. More specifically, the CRCdata generated by the CRC encoding process are used to indicate whetheror not the enhanced data have been damaged while being transmittedthrough the channels. FIG. 5( a) illustrates an example of a CRCencoding process being performed by using an 8-bit checksum with the CRCdata. Herein, a 1-byte CRC checksum (i.e., an 8-bit CRC checksum) isgenerated for 187 bytes of each row within the second RS sub-framegroup. Thereafter, the generated CRC checksum is added to the row.Equation 2 (shown below) shows the equation for generating a 1-byte CRCchecksum for 187 bytes.g(x)x ⁸ +x ² +x ¹+1  Equation 2

In this case, the generated 1-byte CRC checksum may be added in anyplace within the row. In the example given in this embodiment, the CRCchecksum is added at the end of the corresponding row, therebyconfiguring a row of 188 bytes.

FIG. 5( b) and FIG. 5( c) illustrate an example of a CRC encodingprocess being performed by using a 16-bit checksum with the CRC data.Herein, a 2-byte CRC checksum (i.e., a 16-bit CRC checksum) is generatedfor each 2 rows (i.e., 374 bytes). Thereafter, the generated CRCchecksum is added to the corresponding row. Equation 3 (shown below)shows the equation for generating a 2-byte CRC checksum for 2 rows(i.e., 374 bytes.g(x)=x ¹⁶ +x ¹² +x ⁵+1  Equation 3

In this case, the generated 2-byte CRC checksum may be added in anyplace within the 2 rows. In the example given in this embodiment, the2-byte unit CRC checksum is added to a predetermined place within the 2rows, which are then divided into 2 rows configured of 188 bytes. Morespecifically, FIG. 5( b) illustrates an example of adding a 1-byte CRCchecksum at the end of each row, thereby configuring 2 separate rowshaving 188 bytes. FIG. 5( c) illustrates an example of adding a 2-byteCRC checksum at the end of the second row and, then, dividing the 2rows, so as to configure 2 rows having 188 bytes. After being processedwith the above-described CRC encoding process, the first RS sub-framegroup is expanded from a RS sub-frame group having 85*G number of187-byte rows to a RS sub-frame group having 85*G number of 188-byterows. The first RS sub-frame group being processed with CRC encoding isthen divided into G number of first RS sub-frames. The second RSsub-frame group that is processed with row permutation is also dividedinto G number of second RS sub-frames. Thereafter, the newly dividedfirst and second RS sub-frames are inputted to the data processor 102.

FIG. 6( a) illustrates a structure of the first RS sub-frame beingsequentially processed with RS encoding, row permutation, and CRCencoding, which is then inputted to the data processor 102. Herein, thefirst RS sub-frame is configured of 85 188-byte unit rows.Alternatively, FIG. 6( b) illustrates a structure of the second RSsub-frame being sequentially processed with error correction encodingand row permutation, which is then inputted to the data processor 102.Herein, the second RS sub-frame is configured of 85 14-byte unit rows.The data processor 102 takes into consideration the characteristics ofthe hierarchical areas within the data group and the characteristics ofthe first and second RS sub-frames, so as to allocate the first andsecond RS sub-frames to the corresponding areas within the data group.In the present invention, the first RS sub-frames being processed withCRC encoding are allocated to the body area of the data group. Thesecond RS sub-frames being processed with row permutation are allocatedto the head area and/or tail area of the data group. In other words, thedata of the first RS sub-frames are allocated to the body area, and thedata of the second RS sub-frames are allocated to the head area and/ortail area.

Second Embodiment

FIG. 7( a) to FIG. 7( e) illustrate examples showing the steps of anerror correction encoding process according to a second embodiment ofthe present invention. In this embodiment, the inputted enhanced dataare divided into units of an equal length A. A plurality of A-lengthenhanced data units is grouped to configure a RS frame. Then, an errorcorrection encoding process is performed on the configured frame in acolumn direction, thereby adding parity data to the primarily errorcorrection encoded enhanced data in a column direction. In the presentinvention, the particular length A will be referred to as the row forsimplicity. Herein, the value A will be decided by the system designer.Additionally, in this example, the error correction encoding processadopts the RS encoding process. For example, if the inputted enhanceddata correspond to a MPEG transport stream (TS) packet configured of188-byte units, the first MPEG synchronization byte is removed, as shownin FIG. 7( a), thereby configuring a 187-byte row A, as shown in FIG. 7(b).

Herein, the first MPEG synchronization byte is removed because each ofenhanced data packets has the same value. If a fixed byte that can beremoved is not included in the inputted enhanced data, or if the lengthof the inputted packet is not 187 bytes, the input data are divided into187-byte units, thereby configuring a row A divided into 187 bytes. In arow A is decided in accordance with the above-described process, aplurality of rows (A's) is grouped to form a RS frame. As shown in FIG.7( c), in the first embodiment of the present invention, 67 rows aregrouped to form a single RS frame.

A (Nc,Kc)-RS encoding process is performed on each column in the RSframe so as to generate Nc−Kc number of parity bytes. Then, thegenerated Nc−Kc number of parity bytes are added at the end portion ofeach corresponding column (i.e., after the 67^(th) row of eachcorresponding column) In this example, Nc is equal to 91, and Kc isequal to 67 (i.e., Nc=91 and Kc=67). Accordingly, the parity data beingadded to each column, as shown in FIG. 7( d), correspond to 24 bytes.When the (91,67)-RS encoding process is performed on each of the 187columns within the RS frame, a RS frame includes 187 bytes in each rowand 91 bytes in each column. In other words, the RS frame configured asa result of the error correction encoding process includes 91 rows eachconfigured of 187 bytes. In other words, each of the 187 columns withinthe RS frame includes 91 bytes.

As described above, according to the second embodiment of the presentinvention, since the number of bytes configuring each row, the number ofrows configuring the RS frame, and the values of Nc and Kc, which areused for the RS encoding process may vary depending upon the systemdesign and any other circumstances, these details are not limited onlyto the examples given in the first embodiment of the present invention.Meanwhile, a row permutation process may be performed on the primarilyand secondarily RS encoded enhanced data, as described above. Herein, byperforming the row permutation, group errors that may occur duringchanges in a frequency environment may be scattered, thereby enablingthe enhanced data to respond to the frequency environment, which isextremely vulnerable and liable to frequent changes.

More specifically, in the present invention, the error correctionencoded RS frame (i.e., the RS frame having 91 rows each configured of187 bytes) is divided into 2 RS sub-frames. For example, the rows of theenhanced data that are inputted for the RS encoding process (i.e.,payload data) and the rows of the parity data (e.g., rows including 18of the 24 parities generated by a RS encoding process performed in acolumn direction) are collectively referred to as a “first RSsub-frame”. The rows including the remaining 6 parities are referred toas a “second RS sub-frame”. Therefore, the first RS sub-frame includes85 units of 187 bytes, and the second RS sub-frame includes 6 units of187 bytes. Accordingly, a row permutation process is performed on eachof the above-described first RS sub-frame and second RS sub-frame.

FIG. 8 illustrates a row permutation process performed on the first RSsub-frame according to the second embodiment of the present invention,and FIG. 9 illustrates a row permutation process performed on the secondRS sub-frame according to the second embodiment of the presentinvention. The row permutation process performed on the first RSsub-frame shown in FIG. 8 is identical to the row permutation processperformed on the first RS sub-frame according to the first embodiment ofthe present invention. Therefore, a detailed description of the samewill be omitted for simplicity.

Meanwhile, referring to FIG. 9, when a second RS sub-frame including 187bytes in each row and 6 bytes in each column is configured, G number ofsecond RS sub-frames are grouped to configure a second RS sub-framegroup consisting of 6*G number of 187-byte rows. When the rowpermutation process is performed on the above-described second RSsub-frame group by using a predetermined method, the position of therows may differ prior to and after the row permutation process withinthe second RS sub-frame group, as shown in FIG. 9. More specifically,the i^(th) row of the second RS sub-frame group prior to the rowpermutation process is positioned in the j^(th) row of the same secondRS sub-frame after row permutation. Similarly, each row of the second RSsub-frame group is configured of 187 bytes even after the rowpermutation process is performed. The above-described relation between iand j can be easily understood with reference to Equation 4 below.j=G(i mod 6)+└i/6┘i=6(i mod G)+└j/G┘  Equation 4

where 0≦i, j<6G

More specifically, Equation 4 corresponds to a row permutation methodaccording to the second embodiment of the present invention. Any rowpermutation method in which i and j may include all rows within theframe group may be used. The permutation method is not limited only tothe examples given in the description of the present invention. Also inthe second embodiment of the present invention, in using the equationfor performing row permutation on the first and second RS sub-frames,the same equation may be used on both sub-frames, or a differentequation may be used on each sub-frame.

In addition, an error detection encoding process may be performed on thefirst and second RS sub-frame groups that are processed with rowpermutation. The error detection encoding process is used for indicatingwhether the data of the first and second RS sub-frame groups have beendamaged by any error that may occur while the data are being transmittedto the receiving system through the channels. For example, CRC encodingmay be used in the error detection encoding process. Alternatively, anyerror detection encoding method other than the CRC encoding method mayalso be used. Furthermore, an error correction encoding method may beused to enhance the overall error correction performance of thereceiving system. The CRC encoding process, which is performed on thefirst and second RS sub-frame groups according to the second embodimentof the present invention, is identical to the CRC encoding processperformed in the first embodiment of the present invention. Therefore, adetailed description of the same will be omitted for simplicity.

After being processed with the above-described CRC encoding process, thefirst RS sub-frame group is expanded from a RS sub-frame group having85*G number of 187-byte rows to a RS sub-frame group having 85*G numberof 188-byte rows. Similarly, after being processed with theabove-described CRC encoding process, the second RS sub-frame group isexpanded from a RS sub-frame group having 6*G number of 187-byte rows toa RS sub-frame group having 7*G number of 188-byte rows. FIG. 10( a)illustrates a structure of the first RS sub-frame being sequentiallyprocessed with RS encoding, row permutation, and CRC encoding, which isthen inputted to the data processor 102. Herein, the first RS sub-frameis configured of 85 188-byte unit rows. Alternatively, FIG. 10( b)illustrates a structure of the second RS sub-frame being sequentiallyprocessed with error correction encoding, row permutation, CRC encoding,which is then inputted to the data processor 102. Herein, the second RSsub-frame is configured of 6 188-byte unit rows.

The data processor 102 takes into consideration the characteristics ofthe hierarchical areas within the data group and the characteristics ofthe first and second RS sub-frames, so as to allocate the first andsecond RS sub-frames to the corresponding areas within the data group.In the present invention, the first RS sub-frames are allocated to thebody area of the data group. The second RS sub-frames are allocated tothe head area and/or tail area of the data group. In other words, thedata of the first RS sub-frames are allocated to the body area, and thedata of the second RS sub-frames are allocated to the head area and/ortail area. In the description of the first and second embodiments of thepresent invention, any combination of coding rate that satisfies thestructure of the present invention may be used as the RS coding ratesfor the RS encoding process performed in the column direction and the RSencoding process performed in the row direction, respectively. Also,other types of error correction encoding, other than the RS encodingmethod, may also be used in the present invention.

In addition, when performing row permutation, the size of the RSsub-frame is not required to be identical prior to and after rowpermutation. However, only the total number of rows within thecorresponding RS sub-frame group must be identical prior to and afterrow permutation. More specifically, when the size of the RS sub-frameprior to row permutation is equal to G, and the number of rows includedin one RS sub-frame prior to row permutation is equal to N, the rowpermutation process may be performed without any difficulty if thenumber of the RS sub-frames is equal to 2N and if the number of rowsincluded in one RS sub-frame is equal to G/2 (wherein, G is an evennumber). Therefore, the size of each RS sub-frame prior to and after rowpermutation may vary arbitrarily by the system designer.

FIG. 11 to FIG. 13 illustrate examples of a digital broadcasttransmitting system each including the above-described RS frame encoder.The digital broadcast transmitting system of FIG. 11 includes apre-processor 510, a packet multiplexer 521, a data randomizer 522, a RSencoder/non-systematic RS encoder 523, a data interleaver 524, a parityreplacer 525, a non-systematic RS encoder 526, a trellis encoder 527, aframe multiplexer 528, and a transmitting unit 530. The pre-processor510 includes a RS frame encoder 511, a randomizer 512, a block processor513, a group formatter 514, a data deinterleaver 515, and a packetformatter 516. More specifically, the randomizer 512, the blockprocessor 513, the group formatter 514, the data deinterleaver 515, andthe packet formatter 516 collectively correspond to the data processor102 of FIG. 1.

In the above-described structure of the present invention, the main dataare inputted to the packet multiplier 521, and the enhanced data areinputted to the pre-processor 510, which performs additional encoding sothat the enhanced data can respond more effectively to noise and channelenvironment that undergoes frequent changes. The pre-processor 510 ofthe RS frame encoder 511 sequentially performs the RS encoding processand the row permutation process on the enhanced data that are inputtedas shown in the first and second embodiments, and a CRC encoding processmay be performed whenever required. Thereafter, the processed enhanceddata are outputted to the randomizer 512.

More specifically, in the first embodiment of the present invention, aprimary RS encoding process is performed in a column direction on the RSframe that is formed to be processed with error correction. Then, asecondary RS encoding process is performed in a row direction on theprimarily RS error encoded RS frame. Thereafter, the RS encoded RS frameis divided in to first and second RS sub-frames, which are thenrespectively processed with row permutation. Then, a CRC encodingprocess is performed only on the first RS sub-frame, which is thenoutputted to the randomizer 512 (ref. FIG. 2 to FIG. 6). Alternatively,in the second embodiment of the present invention, a RS encoding processis performed in a column direction on the RS frame that is formed to beprocessed with error correction. Thereafter, the RS encoded RS frame isdivided in to first and second RS sub-frames, which are thenrespectively processed with row permutation. Then, a CRC encodingprocess is performed only on the row-permuted first and second RSsub-frames, which are then outputted to the randomizer 512 (ref. FIG. 7to FIG. 10).

The randomizer 512 receives the enhanced data with added robustness fromthe encoding process according to the first and second embodiments. Therandomizer 512, then, randomizes the received enhanced data and outputsthe randomized data to the block processor 513. At this point, by havingthe randomizer 512 randomize the enhanced data, a later randomizingprocess on the enhanced data performed by another randomizer 522 may beomitted. The randomizer of the conventional broadcast system may beidentically used as the randomizer for randomizing the enhanced data.Alternatively, any other type of randomizer may also be used for thisprocess. For example, a pseudo random byte generated from the randomizer512 may be used to randomize the inputted enhanced data.

The block processor 513 encodes the randomized enhanced data at a codingrate of M1/N1. Then, the block processor 513 outputs the M1/N1-rateencoded data to the group formatter 514. For example, if 1 bit of theenhanced data is encoded to 2 bits and outputted, then M1 is equal to 1and N1 is equal to 2 (i.e., M1=1 and N1=2). Alternatively, if 1 bit ofthe enhanced data is encoded to 4 bits and outputted, then M1 is equalto 1 and N1 is equal to 4 (i.e., M1=1 and N1=4). At this point, inprocessing the enhanced data corresponding to the 2 sub-framesidentified as the first RS sub-frame and the second RS sub-frame byusing the randomizer 512 and the block processor 513, the samerandomizer or block processor may be used. On the other hand, a separaterandomizer or block processor may be used. In the example shown in FIG.11, the same randomizer and block processor are used. As describedabove, the group formatter 514 configures a data group based upon apredetermined rule. Thereafter, the received enhanced data are insertedin a corresponding area within the configured data group, which are thenoutputted to the data deinterleaver 515.

FIG. 14 illustrates an alignment of data prior to a data deinterleavingprocess, and FIG. 15 illustrates an alignment of data after the datadeinterleaving process. In other words, FIG. 14 illustrates a dataconfiguration after data interleaving, and FIG. 15 illustrates a dataconfiguration prior to data interleaving. Referring to FIG. 14, in thedata structure prior to data deinterleaving, the data group may bedivided into 3 hierarchical areas: a head area, a body area, and a tailarea. More specifically, based on the data group being data-interleavedand outputted, the portion being outputted first corresponds to the headarea, the portion being outputted next corresponds to the body area, andthe portion being outputted last corresponds to the tail area.

FIG. 14 and FIG. 15 illustrate examples of 260 packets configuring adata group. Since the data interleaver operates at a periodic cycle of52 packets, the example given in the present invention corresponds to amultiple of 52 (i.e., 52*5=260). In addition, with respect to the datagroup being inputted to the data deinterleaver, the head, body and tailareas are set up so that only the enhanced data are included in the bodyarea without being mixed with the main data. For example, the groupformatter 514 inserts the data of the first RS sub-frame, which areencoded at a coding rate of M1/N1 and inputted, into the body areawithin the data group. The group formatter 514 then inserts the data ofthe second RS sub-frame into the head area and/or tail area. Inaddition, apart from the enhanced data, the group formatter 514 alsoallocates signaling information, which indicates overall transmissioninformation, to the body area. More specifically, the signalinginformation corresponds to information required by the receiving systemfor receiving and processing data included in the data group. Herein,the signaling information may include data group information, andmultiplexing information.

With respect to the data deinterleaving process, the group formatter 514inserts a MPEG header place holder, a non-systematic RS parity placeholder, and a main data place holder, as shown in FIG. 14. Herein, asshown in FIG. 14, the main data place is allocated because the enhanceddata are mixed with the main data in the head and tail areas, based uponthe input from the data deinterleaver. Also, with respect to the outputdata after being data-deinterleaved, the place holder for the MPEGheader is allocated at the beginning of each packet. In addition, thegroup formatter 514 either inserts known data, which are generated basedupon a pre-decided method, in a corresponding area, or inserts a knowndata place holder in a corresponding area so as to respectively insertthe known data in a later process. The data group having the data ordata place holder inserted thereto by the group formatter 514 is theninserted to the data deinterleaver 515.

The data deinterleaver 515 performs an inverse process of the datainterleaving process. In other words, the data deinterleaver 515deinterleaves the received data group and outputs the deinterleaved datagroup to the packet formatter 516. The packet formatter 516 removes themain data place holder and the RS parity place holder, which wereallocated for the deinterleaving process, from the receiveddeinterleaved data. Then, the remaining portions of the received dataare gathered (or grouped), and the MPEG header is inserted to replacethe 4-byte MPEG header place holder. Also, in case the group formatter514 inserted the known data place holder, the packet formatter 516 mayeither insert known data in replacement of the known data place holder,or may directly output the known data place holder without anymodification for a replacement insertion in a later process. Thereafter,the packet formatter 516 configures the data within the data group,which is packet-formatted as described above, into a 188-byte unit MPEGTS packet. Then, the packet formatter 516 provides the configured MPEGTS packet to the packet multiplexer 521.

The packet multiplexer 521 multiplexes the 188-byte unit enhanced datapacket, which is outputted from the packet formatter 516, with a maindata packet in accordance with a pre-defined multiplexing method. Then,the packet multiplexer 521 outputs the multiplexed data to the datarandomizer 522. The multiplexing method may be adjusted in accordancewith a plurality of variables of the system design. One of themultiplexing methods of the packet multiplexer 521 is to identify anenhanced data burst section and a main data section along a time axisand alternately repeating the two sections. At this point, at least onedata group may be transmitted from the enhanced data burst section, andonly the main data may be transmitted from the main data section.Herein, the enhanced data burst section may also transmit main data. Asdescribed above, if the enhanced data are transmitted in the burststructure, the receiving system receiving only the enhanced data turnsthe power on only during the burst section in order to receive theenhanced data. Alternatively, the receiving system turns the power offduring the remaining section, which corresponds to the main data sectiontransmitting only the main data, so that the receiving system does notreceive any portion of the main data. Thus, power consumption of thereceiving system may be reduced.

If the inputted data correspond to the main data packet, the datarandomizer 522 performs the same randomizing process as the conventionalrandomizer. More specifically, the data randomizer 522 discards (orremoves) the MPEG synchronization byte included in the main data packetand randomizes the remaining 187 byte by using a pseudo random byte thatis generated by the data randomizer 522. Then, the randomized data bytesare outputted to the RS encoder/non-systematic RS encoder 523. However,if the inputted data correspond to the enhanced data packet, the datarandomizer 522 discards (or removes) the MPEG synchronization byte fromthe 4-byte MPEG header included in the enhanced data packet andrandomizes only the remaining 3 bytes. Also, the data randomizer 522outputs the remaining portion of enhanced data excluding the MPEG headerto the RS encoder/non-systematic RS encoder 523 without performing therandomizing process. This is because the randomizer 512 has alreadyperformed a randomizing process on the enhanced data in an earlierprocess. The known data (or the known data place holder) and theinitialization data place holder included in the enhanced data packetmay either randomized or not randomized.

The RS encoder/non-systematic RS encoder 523 RS-encodes the datarandomized by the data randomizer 522 or the data bypassing the datarandomizer 522 so as to add 20 bytes of RS parity to the correspondingdata. Then, the RS encoder/non-systematic RS encoder 523 outputs theprocessed data to the data interleaver 524. At this point, if theinputted data correspond to the main data packet, the RSencoder/non-systematic RS encoder 523 performs a systematic RS-encodingprocess identical to that of the conventional broadcasting system,thereby adding 20 bytes of RS parity at the end of the 187-byte unitdata. Alternatively, if the inputted data correspond to the enhanceddata packet, the RS encoder/non-systematic RS encoder 523 performs anon-systematic RS-encoding process at a specific parity byte placewithin the enhanced data packet, thereby inserting the 20-byte RSparity. Herein, the data interleaver 524 corresponds to a byte unitconvolutional interleaver. The output of the data interleaver 524 isinputted to the parity replacer 525 and the non-systematic RS encoder526.

Meanwhile, a process of initializing a memory within the trellis encoder527 is primarily required in order to decide the output data of thetrellis encoder 527, which is located after the parity replacer 525, asthe known data pre-defined according to an agreement between thereceiving system and the transmitting system. More specifically, thememory of the trellis encoder 527 should first be initialized before thereceived known data sequence is trellis-encoded. At this point, thebeginning portion of the known data sequence that is being receivedcorresponds to the initialization data place holder and not the actualknown data. Herein, the initialization data place holder has beenincluded in the data by the group formatter 514 in an earlier process.Therefore, the process of generating initialization data and replacingthe initialization data place holder of the corresponding memory withthe generated initialization data are required to be performedimmediately before the known data sequence being inputted istrellis-encoded.

Additionally, a value of the trellis memory initialization data isdecided and generated based upon a memory status of the trellis encoder527. Further, due to the newly replaced initialization data, a processof newly calculating the RS parity and replacing the RS parity, which isoutputted from the data interleaver, with the newly calculated RS parityis required. Therefore, the non-systematic RS encoder 526 receives theenhanced data packet including the initialization data place holder,which is to be replaced with the actual initialization data, from thedata interleaver 524 and also receives the initialization data from thetrellis encoder 527. Among the inputted enhanced data packet, theinitialization data place holder is replaced with the initializationdata, and the RS parity data that are added to the enhanced data packetare removed. Thereafter, a new non-systematic RS parity is calculatedand outputted to the parity replacer 525. Accordingly, the parityreplacer 525 selects the output of the data interleaver 524 as the datawithin the enhanced data packet, and the parity replacer 525 selects theoutput of the non-systematic RS encoder 526 as the RS parity. Theselected data are then outputted to the trellis encoder 527.

Meanwhile, if the main data packet is inputted or if the enhanced datapacket, which does not include any initialization data place holder thatis to be replaced, is inputted, the parity replacer 525 selects the dataand RS parity that are outputted from the data interleaver 524. Then,the parity replacer 525 directly outputs the selected data to thetrellis encoder 527 without any modification. The trellis encoder 527converts the byte-unit data to symbol units and performs a 12-wayinterleaving process so as to trellis-encode the received data.Thereafter, the processed data are outputted to the frame multiplexer528. The frame multiplexer 528 inserts a field synchronization signaland a segment synchronization signal to the data outputted from thetrellis encoder 527 and, then, outputs the processed data to thetransmitting unit 530. Herein, the transmitting unit 530 includes apilot inserter 531, a modulator 532, and a radio frequency (RF)up-converter 533. The operations and roles of the transmitting unit 530and its components are identical to those of the conventionaltransmitter. Therefore, detailed description of the same will be omittedfor simplicity.

The digital broadcast transmitting system of FIG. 12 includes apre-processor 610, a packet multiplexer 521, a data randomizer 522, a RSencoder/non-systematic RS encoder 523, a data interleaver 524, a parityreplacer 525, a non-systematic RS encoder 526, a trellis encoder 527, aframe multiplexer 528, and a transmitting unit 530. The pre-processor610 includes a RS frame encoder 611, a randomizer/byte expansion unit612, a group formatter 613, a block processor 614, a data deinterleaver615, and a packet formatter 616. More specifically, the randomizer/byteexpansion unit 612, the group formatter 613, the block processor 614,the data deinterleaver 615, and the packet formatter 616 collectivelycorrespond to the data processor 102 of FIG. 1. Herein, the differencebetween the digital broadcast transmitting system of FIG. 12 and that ofFIG. 11 is the positioning order of the group formatter and the blockprocessor.

In FIG. 11, the group formatter 514 is located after the block processor513, whereas in FIG. 12, the block processor 614 is placed after thegroup formatter 613. More specifically, in the digital broadcasttransmitting system of FIG. 12, since the group formatter 613 is placedbefore the block processor 614, a byte-expansion process is required tobe performed, in advance, before the group formatter 613 so that theblock processor 614 can respond to the encoding process, therebyfacilitating the operation of the group formatter 613. Therefore, in thedigital broadcast transmitting system of FIG. 12, byte expansion mayalso be performed through randomizing and null data inserting processesby the randomizer/byte expanding unit 612. Conversely, in the digitalbroadcast transmitting system of FIG. 11, the group formatter 514 isplaced before the block processor 513. And, since the encoding processof the block processor 513 directly performs the byte expansion process,a separate byte expansion process is not required. Therefore, thedigital broadcast transmitting system shown in FIG. 11 only randomizesthe enhanced data and does not perform any byte expansion process.

Hereinafter, only a portion of the pre-processor 610 of FIG. 12 will bedescribed in detail, and the other blocks (i.e., reference numerals 521to 528, and 530) may be identically applied as described above in FIG.11. More specifically, the enhanced data are inputted to thepre-processor 610, which performs additional encoding so that theenhanced data can respond more effectively to noise and channelenvironment that undergoes frequent changes. The pre-processor 610 ofthe RS frame encoder 611 receives the enhanced data and configures aframe for the additional encoding process. Then, after performing theencoding process, the RS frame encoder 611 outputs the processed data tothe randomizer/byte expansion unit 612.

The randomizer/byte expansion unit 612 receives the enhanced data withadded robustness from the encoding process. The randomizer/byteexpansion unit 612, then, performs byte expansion by randomizing andinserting null data in the received enhanced data. At this point, byhaving the randomizer/byte expansion unit 612 randomizes the enhanceddata, a later randomizing process on the enhanced data performed byanother randomizer 522 may be omitted. The randomizer of theconventional broadcast system may be identically used as the randomizerfor randomizing the enhanced data. Alternatively, any other type ofrandomizer may also be used for this process.

Herein, the randomizing process and the byte expansion process may alsobe performed in a different order. More specifically, as describedabove, the byte expansion process may be performed after the randomizingprocess. And, conversely, the randomizing process may be performed afterthe byte expansion process. Any method may be selected in accordancewith the overall characteristic of the broadcasting system. Moreover,the byte expansion method may vary in accordance with the encoding rateof the block processor 614. More specifically, if the encoding rate ofthe block processor 614 is M1/N1, the byte expansion unit expands thedata bytes from M1 bytes to N1 bytes. For example, if the encoding rateis ½, then 1 byte is expanded to 2 bytes. Alternatively, if the encodingrate is ¼, then 1 byte is expanded to 4 bytes. The enhanced data beingoutputted from the randomizer/byte expansion unit 612 are inputted tothe group formatter 613. As described in FIG. 11, FIG. 14, and FIG. 15,the group formatter 613 creates (or configures) a data group, and then,the group formatter 613 inserts the received data in corresponding areaswithin the data group. The operations of the group formatter 613 areidentical to those of the group formatter shown in FIG. 11, and,therefore, a detailed description of the same will be omitted forsimplicity.

The data or corresponding place holder inserted in the data group by thegroup formatter 613 is (or are) inputted to the block processor 614. Theblock processor 614 performs additional encoding only on the enhanceddata that are outputted from the group formatter 613. For example, ifthe randomizer/byte expansion unit 612 expanded data from 1 byte to 2bytes, the block processor 614 encodes the enhanced data at a codingrate of ½. Alternatively, if the randomizer/byte expansion unit 612expanded data from 1 byte to 4 bytes, the block processor 614 encodesthe enhanced data at a coding rate of ¼. Additionally, the MPEG headerplace holder, the main data place holder, and the RS parity place holderare to be directly outputted without any data modification. Further, theknown data (or the known data place holder) and the initialization dataplace holder are either set to be directly outputted without any datamodification, or set to be replaced with the known data generated fromthe block processor 614 and then outputted. Herein, the data beingencoded and replaced by the block processor 614 and bypassing blockprocessor 614 are inputted to the data deinterleaver 615. The datadeinterleaver 615 performs an inverse process of the data interleaver524 by deinterleaving the inputted data and outputs the deinterleaveddata to the packet formatter 616.

The packet formatter 616 removes the main data place holder and the RSparity place holder, which were allocated for the deinterleavingprocess, from the deinterleaved data that are being inputted.Thereafter, the packet formatter 616 gathers (or groups) the remainingportions of the data and, then, inserts the MPEG header instead of the4-byte MPEG header place holder. The packet formatter 616 configures thepacket-formatted data in a 188-byte unit MPEG TS packet, which is thensupplied to the packet multiplexer 521. The packet multiplexer 521multiplexes the 188-byte unit enhanced data packet and the main datapacket, which are outputted from the packet formatter 616. Then, themultiplexed data are outputted to the data randomizer 522. The packetmultiplexing method and the later operations are identical to thosedescribed in FIG. 11. Therefore, the detailed description of the samewill be omitted for simplicity.

The digital broadcast transmitting system of FIG. 13 includes apre-processor 710, a packet multiplexer 521, a data randomizer 522, apost-processor 730, a RS encoder/non-systematic RS encoder 523, a datainterleaver 524, a parity replacer 525, a non-systematic RS encoder 526,a trellis encoder 527, a frame multiplexer 528, and a transmitting unit530. The pre-processor 710 includes a RS frame encoder 711, arandomizer/byte expansion unit 712, a group formatter 713, a datadeinterleaver 714, and a packet formatter 715. More specifically, therandomizer/byte expansion unit 712, the group formatter 713, the datadeinterleaver 714, and the packet formatter 715 collectively correspondto the data processor 102 of FIG. 1. Also, the post-processor 730includes a RS parity place holder inserter 731, a data interleaver 732,a block processor 733, a data deinterleaver 734, and a RS parity placeholder remover 735.

In other words, apart from the block processor 614 included in thepre-processor of the digital broadcast transmitting system shown in FIG.12, the pre-processor shown in both FIG. 12 and FIG. 13 have the samestructure and operates identically. Also, the digital broadcasttransmitting system of FIG. 13 further includes a post-processor 730including a block processor 733. Furthermore, the packet multiplexer 521and data randomizer 522 both provided between the pre-processor 710 andthe post-processor 730, the RS encoder/non-systematic RS encoder 523provided after the post-processor 730, the data interleaver 524, theparity replacer 525, the non-systematic encoder 526, the trellis encoder527, the frame multiplexer 528, and the transmitting unit 530 have thesame configuration and operates identically as those of FIG. 11.Therefore, a detailed description of the same will be omitted forsimplicity. Hereinafter, referring to FIG. 13, only the post-processor730 will be described in detail. On the other hand, detailed descriptionof the remaining configuration blocks included in the transmittingsystem, shown in FIG. 13, having the same names as the configurationblocks shown in FIG. 11 or FIG. 12 will be omitted for simplicity.

More specifically, the data randomized by the data randomizer 522 or thedata bypassing the data randomizer 522 are inputted to the RS parityplace holder inserter 731 of the post-processor 730. If the inputteddata correspond to the 187-byte main data packet, the RS parity placeholder inserter 731 inserts a 20-byte RS parity place holder at the endof the 187-byte main data packet. Then, the RS parity place holderinserter 731 outputs the processed data to the data interleaver 732.Alternatively, if the inputted data correspond to the 187-byte enhanceddata packet, a 20-byte RS parity place holder is inserted in theenhanced data packet for the non-systematic RS encoding process, whichwill be performed in a later process. Then, the RS parity place holderinserter 731 inserts the data bytes within the enhanced data packet inthe byte places of the remaining 187 bytes of enhanced data, which arethen outputted to the data interleaver 732. The data interleaver 732performs a data interleaving process on the output of the RS parityplace holder inserter 731 and, then, outputs the interleaved data to theblock processor 733.

The block processor 733 performs additional encoding only on theenhanced data that are outputted from the data interleaver 732. Forexample, if the randomizer/byte expansion unit 712 expanded data from 1byte to 2 bytes, the block processor 733 encodes the enhanced data at acoding rate of ½. Alternatively, if the randomizer/byte expansion unit712 expanded data from 1 byte to 4 bytes, the block processor 733encodes the enhanced data at a coding rate of ¼. The main data or RSparity place holders directly bypass the block processor 733.Additionally, the known data and the initialization data place holderalso bypass the block processor 733. And, the known data place holdermay be replaced by the known data generated from the block processor733, which are then outputted. Herein, the data being encoded andreplaced by the block processor 733 and bypassing block processor 733are inputted to the data deinterleaver 734. The data deinterleaver 734performs an inverse process of the data interleaver 732 bydeinterleaving the inputted data and outputs the deinterleaved data tothe RS parity place holder remover 735.

The RS parity place holder remover 735 removes the 20-byte RS parityplace holder, which was inserted by the RS parity place holder inserter731 for the operations of the data interleaver 732 and the datadeinterleaver 734. Then, the RS parity place holder remover 735 outputsthe processed data to the RS encoder/non-systematic RS encoder 523. Ifthe inputted data correspond to the main data packet, the last 20 bytes,which correspond to the RS parity place holders, are removed from thetotal 207 data bytes. And, if the inputted data correspond to theenhanced data packet, the 20 bytes of the RS parity place holders thatwere inserted to perform the non-systematic RS-encoding process areremoved from the total 207 data bytes. Herein, if the main datasequentially pass through the RS parity place holder inserter 731, thedata interleaver 732, the block processor 733, the data deinterleaver734, and the RS parity place holder remover 735, the main data becomeidentical to the main data that were originally inputted to the RSparity place holder inserter 731. As described above, the embodiments ofthe digital broadcast transmitting system of the present invention shownin FIG. 11 to FIG. 13 are merely exemplary. Herein, any transmittingsystem that can perform additional error correction encoding on theenhanced data may be used in the present invention. And, therefore, thepresent invention is not limited to the examples set forth herein.

Meanwhile, the randomizer 512 of the transmitting system shown in FIG.11 may be placed before the RS frame encoder 511. Also, only therandomizing function of the randomizer/byte expansion unit 612 or 712 ofthe transmitting system shown in FIG. 12 or FIG. 13 may be placed beforethe RS frame encoder. In this case, a derandomizing function included ina data deformatter 805 shown in FIG. 16 may be placed behind the RSframe encoder 806. And, if the randomizer is placed at the fore-end ofthe pre-processor 510, 610 or 710 within the transmitting system shownin FIG. 11, FIG. 12 or FIG. 13, the function of removing the MPEGsynchronization byte, which is originally performed at the RS frameencoder 511, 611 or 711, may be placed in the randomizer.

FIG. 16 illustrates a block diagram showing a demodulating unit of adigital broadcast receiving system according to an embodiment of thepresent invention, wherein the demodulating unit is used for receivingdata transmitted from the transmitting system, demodulating andequalizing the received data, so as to recover the processed data backto the initial (or original) data. Referring to FIG. 8, the demodulatingunit of the digital broadcast receiving system includes a demodulator801, an equalizer 802, a known sequence detector 803, a block decoder804, a data deformatter 805, a RS frame decoder 806, a datadeinterleaver 807, a RS decoder 808, and a derandomizer 809.

More specifically, an intermediate frequency (IF) signal of a particularchannel that is tuned by a tuner is inputted to the demodulator 801 andthe known sequence detector 803. The demodulator 801 performs self gaincontrol, carrier recovery, and timing recovery processes on the inputtedIF signal, thereby modifying the IF signal to a baseband signal. Then,the demodulator 801 outputs the newly created baseband signal to theequalizer 802 and the known sequence detector 803. The equalizer 802compensates the distortion of the channel included in the demodulatedsignal and then outputs the error-compensated signal to the blockdecoder 804.

At this point, the known sequence detector 803 detects the knownsequence place inserted by the transmitting end from the input/outputdata of the demodulator 801 (i.e., the data prior to the demodulation orthe data after the modulation). Thereafter, the place information alongwith the symbol column of the known sequence, which is generated fromthe detected place, is outputted to the demodulator 801, the equalizer802, and the block decoder 804. Also, the known sequence detector 803outputs a set of information to the block decoder 804. This set ofinformation is used to allow the block decoder 804 of the receivingsystem to identify the enhanced data that are processed with additionalencoding from the transmitting system and the main data that are notprocessed with additional encoding. This set of information is also usedto indicate a stating point of a block in the enhanced encoder. Inaddition, although the connection status is not shown in FIG. 10, theinformation detected from the known sequence detector 803 may be usedthroughout the entire receiving system and may also be used in the datadeformatter 805 and the RS frame decoder 806.

The demodulator 801 uses the known data symbol column during the timingand/or carrier recovery, thereby enhancing the demodulating performance.Similarly, the equalizer 802 uses the known data sequence, therebyenhancing the equalizing quality. Moreover, the decoding result of theblock decoder 804 may be fed-back to the equalizer 802, therebyenhancing the equalizing performance. Meanwhile, if the data that areinputted to the block decoder 804 from the equalizer 802 correspond tothe enhanced data being processed with both additional encoding andtrellis encoding by the transmitting system, trellis decoding andadditional decoding processes are performed as inverse processes of thetransmitting system. Alternatively, if the data that are inputted to theblock decoder 804 from the equalizer 802 correspond to the main databeing processed only with the trellis encoding process and not theadditional encoding process, then only the trellis decoding process isperformed. The data group decoded by the block decoder 804 is inputtedto the data deformatter 805, and the main data packet is inputted to thedata deinterleaver 807.

More specifically, if the inputted data correspond to the main data, theblock decoder 804 performs Viterbi decoding on the input data, so as toeither output a hard decision value or to perform hard decision on asoft decision value and, accordingly, output the hard decided result. Onthe other hand, if the input data correspond to the enhanced data, theblock decoder 804 outputs either a hard decision value or a softdecision value on the inputted enhanced data. If the inputted datacorrespond to the enhanced data, the block decoder 804 performs adecoding process on the data encoded by the block processor and thetrellis encoder of the transmitting system. At this point, the dataoutputted from a block encoder of the pre-processor may correspond to anexternal code, and the data outputted from any one of the blockprocessor and the trellis encoder may correspond to an internal code.Therefore, in order to maximize the encoding performance of the externalcode when decoding such concatenated codes, a soft decision value shouldbe outputted from the decoder of the internal code.

Accordingly, the block decoder 804 may output a hard decision value onthe enhanced data. And, if required, it is preferable for the blockdecoder 804 to output a soft decision value. More specifically,depending upon the system design or conditions, the block decoder 804outputs any one of the soft decision value and the hard decision valuewith respect to the enhanced data, and the block decoder 804 outputs thehard decision value with respect to the main data. Meanwhile, the datadeinterleaver 807, the RS decoder 808, and the derandomizer 809 areconfiguration blocks required for receiving the main data. Therefore, ina receiving system that is structured for receiving only the enhanceddata, the above-mentioned configuration blocks may not be required inthe structure.

The data deinterleaver 807 performs an inverse process of the datainterleaver. In other words, the data deinterleaver 807 deinterleavesthe main data and outputs the deinterleaved main data to the RS decoder808. The RS decoder 808 performs a systematic RS decoding process on thedeinterleaved data and outputs the processed data to the derandomizer809. The derandomizer 809 receives the output of the RS decoder 808 andgenerates a pseudo random data byte identical to that of the randomizerincluded in the digital broadcast transmitting system (or DTVtransmitter). Thereafter, the derandomizer 809 performs a bitwiseexclusive OR (XOR) operation on the generated pseudo random data byte,thereby inserting the MPEG synchronization bytes to the beginning ofeach packet so as to output the data in 188-byte main data packet units.

Meanwhile, the data being outputted from the block decoder 804 to thedata deformater 805 are inputted in the form of a data group. At thispoint, the data deformatter 805 already knows the structure of the datathat are to be inputted and is, therefore, capable of identifying thesignaling information, which includes the system information, and theenhanced data from the body area within the data group. Herein, the datadeformatter 805 removes the known data, trellis initialization data, andMPEG header that were inserted to the main data and the data group, andalso removes the RS parity that was added from the RSencoder/non-systematic RS encoder or non-systematic RS encoder of thetransmitting system. Then, the data deformatter 805 outputs theprocessed data.

Thereafter, the data deformatter 805 performs an inverse process of therandomizer/byte expansion unit in the transmitting system by performinga derandomizing process on the enhanced data. At this point, the nulldata which were inserted for data expansion may or may not be requiredto be removed. In other words, depending upon the design of thereceiving system, a unit for removing the byte that was expanded by thebyte expansion unit of the transmitting system may be required. However,if the null data that were inserted at the time of the byte expansionare removed and if the null-data-removed data are outputted, theexpanded byte is not required to be removed. If the expanded byte isrequired to be removed, the order of the process of removing theexpanded data and the process of derandomizing the data may be changeddepending upon the design of the transmitting system. More specifically,if byte expansion is performed after data-randomizing in thetransmitting system, then data-derandomizing is performed after byteremoval in the receiving system. Alternatively, if data-randomizing isperformed after byte expansion in the transmitting system, then byteremoval is performed after data-derandomizing in the receiving system.

Furthermore, during the derandomizing process, if the RS frame decoder806 requires soft decision and, accordingly, receives the soft decisionvalue from the block decoder 804, it is difficult to perform a bitwiseexclusive OR (XOR) operation between the soft decision value and thepseudo random bit, which is used for derandomizing. Therefore, when anXOR operation is performed between the pseudo random bit and the softdecision value of the enhanced data bit, and when the pseudo random bitis equal to ‘1’, the data deformatter 805 changes the code of the softdecision value and then outputs the changed code. On the other hand, ifthe pseudo random bit is equal to ‘0’, the data deformatter 805 outputsthe soft decision value without any change in the code. Thus, the softdecision status may be maintained and transmitted to the RS framedecoder 806.

If the pseudo random bit is equal to ‘1’ as described above, the code ofthe soft decision value is changed because, when an XOR operation isperformed between the pseudo random bit and the input data in therandomizer of the transmitting system, and when the pseudo random bit isequal to ‘1’, the code of the output data bit becomes the opposite ofthe input data (i.e., 0 XOR 1=1 and 1 XOR 0=0). More specifically, ifthe pseudo random bit generated from the data deformatter 805 is equalto ‘1’, and when an XOR operation is performed on the hard decisionvalue of the enhanced data bit, the XOR-operated value becomes theopposite value of the hard decision value. Therefore, when the softdecision value is outputted, a code opposite to that of the softdecision value is outputted. The RS frame decoder 806 performs aninverse process of the RS frame encoder included in the transmittingsystem and, then, outputs the processed enhanced data.

In the description of the transmitting system, the encoding process ofthe RS frame encoder was described according to first and secondembodiments of the present invention. Therefore, in the description ofthe receiving system, the decoding process of the RS frame decoder 806will hereinafter be described according to third and fourth embodimentof the present invention, respectively.

Third Embodiment

In the third embodiment of the present invention, a decoding process isperformed on the enhanced data processed with the encoding process andtransmitted from the transmitting system according to the firstembodiment of the present invention. FIG. 17 illustrates a flow chartshowing the general steps of the RS encoding process according to thethird embodiment of the present invention. More specifically, referringto FIG. 17, when the present invention is unable to correct all errorsby decoding only the first RS sub-frame, the present invention performsdecoding by using the second RS sub-frame also. In the example of thepresent invention, when the number of errors within the enhanced data ofthe body area (i.e., the first RS sub-frame) is equal to or greater thana predetermined number, or when not all of the errors are correctedafter decoding only the first RS sub-frame, the enhanced data of thehead/tail area(s) (i.e., the second RS sub-frame) are additionally usedto perform decoding. Hereinafter, the RS decoding process according tothe third embodiment of the present invention will now be described indetail.

The RS frame decoder 806 groups (or gathers) G number of first RSsub-frames, which are transmitted to the body area, so as to create afirst RS sub-frame group of 85*G 187-byte units. And, when using a1-byte CRC (i.e., an 8-bit CRC), as shown in FIG. 5( a), each of the188-byte packets is verified for existing errors. Then, after removingthe 1-byte CRC checksum and leaving only 187 bytes, the presence of anerror is indicated by an error flag corresponding to the packet. On theother hand, when using a 2-byte CRC (i.e., a 16-bit CRC), as shown inFIG. 5( b) and FIG. 5( c), two 188-byte packets are verified forexisting errors. Then, the 2-byte CRC checksum is removed, therebycreating 2 187-byte packets. Thereafter, the presence of an error isindicated by an error flag corresponding to each of the packets,respectively. Herein, when using the 2-byte CRC checksum, errors shouldbe indicated to exist either in both packets or in none of the twopackets.

After checking for any error in each row by using the CRC checksum, aninverse process of the row permutation process is performed on the firstRS sub-frame group, so as to align the first RS sub-frame groupconfigured of 85*G 187-byte units, thereby aligning the first RSsub-frame group in the transmitting system (S901). Thereafter, the firstRS sub-frame group is divided into G number of first RS sub-frames,which are configured of 85 187-byte units. When performing the inverseprocess of row permutation, the error flags corresponding to each packet(or row), and which indicates whether an error exists or not, are alsochanged and succeeded accordingly. Each RS frame is configured as a187×85 byte matrix.

The RS frame decoder 806 also groups G number of second RS sub-framesthat are being transmitted to the head/tail areas, thereby creating asecond RS sub-frame group formed of 85*G second RS sub-frames. Then, theRS frame decoder 806 performs an inverse process of row permutation onthe second RS sub-frame group and aligns the second RS sub-frame groupto its initial order prior to being processed with row permutation atthe transmitting system (S901). Subsequently, the second RS sub-framegroup is divided into G number of second RS sub-frames, which areconfigured of 85 14-byte units. Since the transmitting system did notprocess the second RS sub-frame group, which is transmitted to thehead/tail areas, with CRC encoding, the receiving system does notperform CRC decoding on the second RS sub-frame group.

After the inverse process of row permutation, the error flags indicatingthe presence of errors in each packet (or row), which are succeededalong with the first RS sub-frame, are used to perform the RS decodingprocess (S902). Herein, in Step 903, a CRC error flag corresponding toeach row within the first RS sub-frame is verified in order to determinewhether the number of rows having errors within the first RS sub-frameis equal to or smaller than a maximum number of errors (=Nc−Kc) that canbe corrected by erasure, when performing RS decoding in a columndirection. If it is determined that the number of rows within the firstRS sub-frame having errors existing therein is equal to or smaller thanthe maximum number of errors that can be corrected by erasure,(85,67)-RS erasure decoding is performed in a column direction on thefirst RS sub-frame having 85 187-byte rows, and the 18 parity data bytesadded at the end of each column are removed (S904 and S908).Accordingly, as shown in Step 908, a RS frame configured of 67 187-byterows (or packets) may be obtained. And, as shown in Step 909, the MPEGsynchronization byte, which was removed from the foremost portion (orbeginning) of each 187-byte row is added once again, so that an enhancedTS packet recovered back to 188 bytes is outputted.

Meanwhile, in Step 903, if it is determined that the number of rowswithin the first RS sub-frame having errors existing therein is largerthan the maximum number of errors (=Nc−Kc) that can be corrected byerasure, (85,67)-RS erasure decoding is performed in a column directionon the first RS sub-frame having 85 187-byte rows (S905). Then, basedupon the result of performing the (85,67)-RS erasure decoding process,it is determined whether all of the errors within the first RS sub-frameare corrected (S906). Based upon the result of the (85,67)-RS decodingprocess of Step 906, if it is determined that all errors are corrected,the 18 parity data bytes that were added at the end of each column areremoved. Then, a RS frame configured of 67 187-byte rows (or packets)may be obtained, as shown in Step 908. And, as shown in Step 909, theMPEG synchronization byte, which was removed from the foremost portion(or beginning) of each 187-byte row, is added once again so as to outputan enhanced TS packet that is recovered back to 188 bytes.Alternatively, if the result of the (85,67)-RS decoding process of Step906 determines that not all errors are corrected, then RS decoding isperformed by combining the first RS sub-frame and the second RSsub-frame (S907).

FIG. 18 illustrates an example of combining the first RS sub-frame,which is transmitted to the body area, and the second RS sub-frame,which is transmitted to the head/tail areas, in Step 907, so as toperform RS decoding. When the first RS sub-frame is merged with thesecond RS sub-frame, each RS sub-frame being processed with inverseprocesses of row permutation, the RS frame having 85 201-byte packets(or rows) may be obtained, as shown in FIG. 18( a). At this point, eachRS frame has already been individually processed with double RS encodingby the transmitting. Therefore, the RS frame decoder 806 performs adouble RS decoding process, as an inverse process of the double RSencoding performed by the transmitting system.

For example, if (85,67)-RS encoding was performed in a column direction,and if the RS-encoded result was processed with (201,187)-RS encoding ina row direction, as shown in FIG. 2, the RS frame decoder 806 performs(201,187)-RS decoding (i.e., primary RS decoding) in a row direction oneach RS frame, as shown in FIG. 18( a). Subsequently, the RS framedecoder 806 performs (85,67)-RS decoding (i.e., secondary RS decoding)in a column direction on each RS frame, as shown in FIG. 18( b). At thispoint, FIG. 18( a) illustrates an example of performing (201,187)-RSencoding in a row direction on a RS frame having 85 201-byte rows. And,FIG. 18( b) illustrates an example of performing (85,67)-RS decoding ina column direction on a RS frame having 85 187-byte rows. Thereafter, inaccordance with a pre-determined condition, the RS decoding process in acolumn direction and the RS decoding process in a row direction areeither repeated or the decoding process is ended.

Herein, the pre-determined condition may be selected from a selection ofconditions. In the example given in the present invention, whether ornot to repeat the decoding process is decided based upon thepre-determined number of repetition and the number of error that arecorrected by performing the secondary RS decoding process. Morespecifically, if the decoding process is repeated as much as thepre-determined maximum number of repetition, or if additional errorcorrection is not performed as a result of the secondary RS decodingprocess, the decoding process is ended. Otherwise, the primary RSdecoding process and the secondary RS decoding process are continuouslyrepeated. Once the (85,67)-RS decoding process is performed in a columndirection, as shown in FIG. 18( b), a process of verifying whether thepre-determined maximum number of repetition is completed or whether nota single data byte has been error corrected as a result of the RSdecoding process performed in a column direction is carried out, asshown in FIG. 18( c).

At this point, as shown in FIG. 18( c), if the pre-determined maximumnumber of repetition still remains, and if at least one data byte hasbeen error corrected after performing the RS decoding process in acolumn direction, the process step returns to the step shown in FIG. 18(a), thereby performing once again the RS decoding process in a rowdirection on the RS frame RS-decoded in a column direction. Morespecifically, as a result of the RS decoding process performed in acolumn direction, if at least one error corrected data byte exists, andif a RS decoding process is performed in a row direction on the RS framethat has been RS decoded in a column direction, there is a possibilityof performing additional error correction during the process ofperforming RS decoding in a row direction. Moreover, if a RS decodingprocess is performed once again in a column direction on the RS framethat has been additionally error corrected after being processed with aRS decoding process in a row direction, there is also a possibility ofperforming additional error correction.

Therefore, in the present invention, if at least one error correcteddata byte exists as a result of a RS decoding process performed in acolumn direction within the pre-determined range of number of repeatingthe decoding process, the RS decoding process is repeated in both rowand column directions while reflecting the error corrected results inorder to enhanced the decoding performance. At this point, if the RSdecoding process is repeated in both row and column directions, errorsare continuously corrected so as to enhance the decoding performance.However, in a particular state of error, an error may be corrected bythe RS decoding process performed in a row direction, while anothererror may occur in a row direction due to a RS decoding processperformed in a column direction. This may eventually lead to an endlessrepetition of correcting and creating errors. Therefore, in the presentinvention, the number of repetition is limited in order to prevent suchendless repetition of correcting and creating errors from occurring.

Furthermore, when there is no error corrected data byte as a result of aRS decoding process performing in a column direction, this indicatesthat an error no longer exists within the RS frame. Therefore, there isno need to repeat the RS decoding process. Accordingly, as shown in FIG.18( c), if the pre-determined maximum number of repetition is completed,and if not a single data byte is error corrected after performing the RSdecoding process in a column direction, the RS decoding process isended, as shown in FIG. 18( d), and the 14-byte parity data added at theend of each row and the 18-byte parity data added at the end of eachcolumn, which are added while performing the double RS decoding process,are removed. Thus, an RS frame configured of 67 187-byte rows (orpackets) may be obtained, as shown in FIG. 18( d).

Finally, as shown in FIG. 18( e), the MPEG synchronization byte, whichwas removed from the foremost portion (or beginning) of each 187-byterow, is added once again so as to output an enhanced TS packet that isrecovered back to 188 bytes. Herein, the number of repetition and thenumber of error corrected data bytes, both deciding whether to repeatthe RS decoding process, may vary according to the design of the systemdesigner. Therefore, the conditions are not limited only to the examplesset forth in the description of the present invention.

Fourth Embodiment

In the fourth embodiment of the present invention, a decoding process isperformed on the enhanced data processed with the encoding process andtransmitted from the transmitting system according to the secondembodiment of the present invention. FIG. 19 illustrates a flow chartshowing the general steps of the RS encoding process according to thefourth embodiment of the present invention. More specifically, referringto FIG. 19, the RS decoding process may vary in accordance with the sumof the number of errors within the first RS sub-frame, which istransmitted to the body area within the data group, and the number oferrors within the second RS sub-frame, which is transmitted to thehead/tail areas within the data group.

In order to do so, the RS frame decoder 806 groups (or gathers) G numberof first RS sub-frames, which are transmitted to the body area, so as tocreate a first RS sub-frame group of 85*G 187-byte units. Herein, afirst RS sub-frame is configured of 85 187-byte rows (or packets), asshown in FIG. 18( a). And, when using a 1-byte CRC (i.e., an 8-bit CRC),as shown in FIG. 5( a), each of the 188-byte packets within the first RSsub-frame group is verified for existing errors. Then, after removingthe 1-byte CRC checksum and leaving only 187 bytes, the presence of anerror is indicated by an error flag corresponding to the packet. On theother hand, when using a 2-byte CRC (i.e., a 16-bit CRC), as shown inFIG. 5( b) and FIG. 5( c), two 188-byte packets are verified forexisting errors. Then, the 2-byte CRC checksum is removed, therebycreating 2 187-byte packets. Thereafter, the presence of an error isindicated by an error flag corresponding to each of the packets,respectively. Herein, when using the 2-byte CRC checksum, errors shouldbe indicated to exist either in both packets or in none of the twopackets.

After checking for any error in each row by using the CRC checksum, aninverse process of the row permutation process is performed on the firstRS sub-frame, as shown in FIG. 19( b), so as to align the first RSsub-frame group configured of 85*G 187-byte units, thereby aligning thefirst RS sub-frame group in the transmitting system. Thereafter, thefirst RS sub-frame group is divided into G number of first RSsub-frames, which are configured of 85 187-byte units. When performingthe inverse process of row permutation, the error flags corresponding toeach packet (or row), and which indicates whether an error exists ornot, are also changed and succeeded accordingly.

The RS frame decoder 806 also groups G number of second RS sub-framesthat are being transmitted to the head/tail areas, thereby creating asecond RS sub-frame group formed of 6*G second RS sub-frames. Herein, asecond RS sub-frame is configured of 6 187-byte rows (or packets), asshown in FIG. 18( a). And, when using a 1-byte CRC (i.e., an 8-bit CRC),as shown in FIG. 5( a), each of the 188-byte packets within the first RSsub-frame group is verified for existing errors. Then, after removingthe 1-byte CRC checksum and leaving only 187 bytes, the presence of anerror is indicated by an error flag corresponding to the packet. On theother hand, when using a 2-byte CRC (i.e., a 16-bit CRC), as shown inFIG. 5( b) and FIG. 5( c), two 188-byte packets are verified forexisting errors. Then, the 2-byte CRC checksum is removed, therebycreating 2 187-byte packets. Thereafter, the presence of an error isindicated by an error flag corresponding to each of the packets,respectively. Herein, when using the 2-byte CRC checksum, errors shouldbe indicated to exist either in both packets or in none of the twopackets.

After checking for any error in each row by using the CRC checksum, aninverse process of the row permutation process is performed on thesecond RS sub-frame group, as shown in FIG. 19( b), so as to align thesecond RS sub-frame group configured of 6*G 187-byte units, therebyaligning the second RS sub-frame group in the transmitting system.Thereafter, the second RS sub-frame group is divided into G number ofsecond RS sub-frames, which are configured of 6 187-byte units.Similarly, when performing the inverse process of row permutation, theerror flags corresponding to each packet (or row), and which indicateswhether an error exists or not, are also changed and succeededaccordingly.

At this point, when the first and second RS sub-frames, which areprocessed with the inverse process of row permutation, are combined, aRS frame having 91 packets (or rows) configured of 187 bytes isobtained. As shown in FIG. 19( c), a process of verifying whether thetotal number of CRC errors occurring in the RS frame is greater than thenumber of parity bytes added to the RS frame. Herein, the total numberof CRC errors occurring in the RS frame may be known by verifying theCRC error flag corresponding to each row within the RS frame. And, thenumber of parity bytes added to the RS frame may be known by performingNc−Kc. If the total number of CRC errors occurring in the RS frame isequal to or smaller than the number of parity bytes added to the RSframe, the values of the 91 CRC error flags corresponding to each rowwithin the RS frame are used, as shown in FIG. 19( d), therebyperforming a (91,67)-RS erasure decoding process in each columndirection of the RS frame.

Meanwhile, if the total number of CRC errors occurring in the RS frameis greater than the number of parity bytes added to the RS frame, thevalues of the 6 CRC error flags corresponding to each row of the secondRS sub-frame within the RS frame are used, as shown in FIG. 19( e),thereby performing a (91,67)-RS erasure decoding process in each columndirection of the RS frame. In another embodiment of the presentinvention, if the total number of CRC errors occurring in the RS frameis greater than the number of parity bytes added to the RS frame, a(91,67)-RS decoding process may be performed without using the CRC errorflag values.

When the RS decoding process is performed on each RS frame, as shown inFIG. 19( d) or FIG. 19( e), the 24 parity bytes that were added to theend of each column when performing the RS encoding process are removed.Thus, a RS frame configured of 67 187-byte rows (or packets) may beobtained, as shown in FIG. 19( f). Furthermore, as shown in FIG. 19( g),the MPEG synchronization byte, which was removed from the foremostportion (or beginning) of each 187-byte row, is added once again so asto output an enhanced TS packet that is recovered back to 188 bytes.

FIG. 20 illustrates a block diagram showing the structure of a digitalbroadcast transmitting system according to an embodiment of the presentinvention. The digital broadcast (or DTV) transmitting system includes apre-processor 1110, a packet multiplexer 1121, a data randomizer 1122, aReed-Solomon (RS) encoder/non-systematic RS encoder 1123, a datainterleaver 1124, a parity byte replacer 1125, a non-systematic RSencoder 1126, a frame multiplexer 1128, and a transmitting system 1130.The pre-processor 1110 includes an enhanced data randomizer 1111, a RSframe encoder 1112, a block processor 1113, a group formatter 1114, adata deinterleaver 1115, and a packet formatter 1116.

In the present invention having the above-described structure, main dataare inputted to the packet multiplexer 1121. Enhanced data are inputtedto the enhanced data randomizer 1111 of the pre-processor 1110, whereinan additional coding process is performed so that the present inventioncan respond swiftly and appropriately against noise and change inchannel. The enhanced data randomizer 1111 randomizes the receivedenhanced data and outputs the randomized enhanced data to the RS frameencoder 1112. At this point, by having the enhanced data randomizer 1111perform the randomizing process on the enhanced data, the randomizingprocess on the enhanced data by the data randomizer 1122 in a laterprocess may be omitted. Either the randomizer of the conventionalbroadcast system may be used as the randomizer for randomizing theenhanced data, or any other type of randomizer may be used herein.

The RS frame encoder 1112 receives the randomized enhanced data andperforms at least one of an error correction coding process and an errordetection coding process on the received data. Accordingly, by providingrobustness to the enhanced data, the data can scatter group error thatmay occur due to a change in the frequency environment. Thus, the datacan respond appropriately to the frequency environment which is verypoor and liable to change. The RS frame multiplexer 1112 also includes aprocess of mixing in row units many sets of enhanced data each having apre-determined size. By performing an error correction coding process onthe inputted enhanced data, the RS frame encoder 1112 adds data requiredfor the error correction and, then, performs an error detection codingprocess, thereby adding data required for the error detection process.The error correction coding uses the RS coding method, and the errordetection coding uses the cyclic redundancy check (CRC) coding methodwhen performing the RS coding process, parity data required for theerror correction are generated. And, when performing the CRC codingprocess, CRC data required for the error detection are generated.

The RS frame encoder 1112 performs CRC coding on the RS coded enhanceddata in order to create the CRC code. The CRC code that is generated bythe CRC coding process may be used to indicate whether the enhanced datahave been damaged by an error while being transmitted through thechannel. The present invention may adopt other types of error detectioncoding methods, apart from the CRC coding method, and may also use theerror correction coding method so as to enhance the overall errorcorrection ability of the receiving system. For example, assuming thatthe size of one RS frame is 187*N bytes, that (235,187)-RS codingprocess is performed on each column within the RS frame, and that a CRCcoding process using a 2-byte (i.e., 16-bit) CRC checksum, then a RSframe having the size of 187*N bytes is expanded to a RS frame of235*(N+2) bytes. The RS frame expanded by the RS frame encoder 1112 isinputted to the block processor 1113. The block processor 1113 codes theRS-coded and CRC-coded enhanced data at a coding rate of M1/N1. Then,the block processor 1113 outputs the M1/N1-rate coded enhanced data tothe group formatter 1114. In order to do so, the block processor 1113identifies the block data bytes being inputted from the RS frame encoder1112 as bits.

The block processor 1113 may receive supplemental information data suchas signaling information, which include information on the system, andidentifies the supplemental information data bytes as data bits. Herein,the supplemental information data, such as the signaling information,may equally pass through the enhanced data randomizer 1111 and the RSframe encoder 1112 so as to be inputted to the block processor 1113.Alternatively, the supplemental information data may be directlyinputted to the block processor 1113 without passing through theenhanced data randomizer 1111 and the RS frame encoder 1112. Thesignaling information corresponds to information required for receivingand processing data included in the data group in the receiving system.Such signaling information includes data group information, multiplexinginformation, and burst information.

As a M1/N1-rate encoder, the block processor 1113 codes the inputteddata at a coding rate of M1/N1 and then outputs the M1/N1-rate codeddata. For example, if 1 bit of the input data is coded to 2 bits andoutputted, then M1 is equal to 1 and N1 is equal to 2 (i.e., M1=1 andN1=2). Alternatively, if 1 bit of the input data is coded to 4 bits andoutputted, then M1 is equal to 1 and N1 is equal to 4 (i.e., M1=1 andN1=4). As an example of the present invention, it is assumed that theblock processor 1113 performs a coding process at a coding rate of ½(also referred to as a ½-rate coding process) or a coding process at acoding rate of ¼ (also referred to as a ¼-rate coding process). Morespecifically, the block processor 1113 codes the received enhanced dataand supplemental information data, such as the signaling information, ateither a coding rate of ½ or a coding rate of ¼. Thereafter, thesupplemental information data, such as the signaling information, areidentified and processed as enhanced data.

Since the ¼-rate coding process has a higher coding rate than the ½-ratecoding process, greater error correction ability may be provided.Therefore, in a later process, by allocating the ¼-rate coded data in anarea with deficient receiving performance within the group formatter1114, and by allocating the ½-rate coded data in an area with excellentreceiving performance, the difference in the overall performance may bereduced. More specifically, in case of performing the ½-rate codingprocess, the block processor 1113 receives 1 bit and codes the received1 bit to 2 bits (i.e., 1 symbol). Then, the block processor 1113 outputsthe processed 2 bits (or 1 symbol). On the other hand, in case ofperforming the ¼-rate coding process, the block processor 1113 receives1 bit and codes the received 1 bit to 4 bits (i.e., 2 symbols). Then,the block processor 1113 outputs the processed 4 bits (or 2 symbols).Additionally, the block processor 1113 performs a block interleavingprocess in symbol units on the symbol-coded data. Subsequently, theblock processor 1113 converts to bytes the data symbols that areblock-interleaved and have the order rearranged.

The group formatter 1114 inserts the enhanced data outputted from theblock processor 1113 (herein, the enhanced data may include supplementalinformation data such as signaling information including transmissioninformation) in a corresponding area within the data group, which isconfigured according to a pre-defined rule. Furthermore, in relationwith the data deinterleaving process, various types of places holders orknown data are also inserted in corresponding areas within the datagroup. At this point, the data group may be described by at least onehierarchical area. Herein, the data allocated to the each area may varydepending upon the characteristic of each hierarchical area.Additionally, each data group may be configured to include a fieldsynchronization signal.

In another example given in the present invention, a data group isdivided into A, B, and C regions in a data configuration prior to datadeinterleaving.

FIG. 21 illustrates an alignment of data before being data deinterleavedand identified, and FIG. 22 illustrates an alignment of data after beingdata deinterleaved and identified. More specifically, a data structureidentical to that shown in FIG. 21 is transmitted to a receiving system.Also, the data group configured to have the same structure as the datastructure shown in FIG. 21 is inputted to the data deinterleaver 1115.

As described above, FIG. 21 illustrates a data structure prior to datadeinterleaving that is divided into 3 regions, such as region A, regionB, and region C. Also, in the present invention, each of the regions Ato C is further divided into a plurality of regions. Referring to FIG.21, region A is divided into 5 regions (A1 to A5), region B is dividedinto 2 regions (B1 and B2), and region C is divided into 3 regions (C1to C3). Herein, regions A to C are identified as regions having similarreceiving performances within the data group. Herein, the type ofenhanced data, which are inputted, may also vary depending upon thecharacteristic of each region.

In the example of the present invention, the data structure is dividedinto regions A to C based upon the level of interference of the maindata. Herein, the data group is divided into a plurality of regions tobe used for different purposes. More specifically, a region of the maindata having no interference or a very low interference level may beconsidered to have a more resistant (or stronger) receiving performanceas compared to regions having higher interference levels. Additionally,when using a system inserting and transmitting known data in the datagroup, and when consecutively long known data are to be periodicallyinserted in the enhanced data, the known data having a predeterminedlength may be periodically inserted in the region having no interferencefrom the main data (e.g., region A). However, due to interference fromthe main data, it is difficult to periodically insert known data andalso to insert consecutively long known data to a region havinginterference from the main data (e.g., region B and region C).

Hereinafter, examples of allocating data to region A (A1 to A5), regionB (B1 and B2), and region C (C1 to C3) will now be described in detailwith reference to FIG. 21. The data group size, the number ofhierarchically divided regions within the data group and the size ofeach region, and the number of enhanced data bytes that can be insertedin each hierarchically divided region of FIG. 21 are merely examplesgiven to facilitate the understanding of the present invention. Herein,the group formatter 1114 creates a data group including places in whichfield synchronization bytes are to be inserted, so as to create the datagroup that will hereinafter be described in detail.

More specifically, region A is a region within the data group in which along known data sequence may be periodically inserted, and in whichincludes regions wherein the main data are not mixed (e.g., A1 to A5).Also, region A includes a region (e.g., A1) located between a fieldsynchronization region and the region in which the first known datasequence is to be inserted. The field synchronization region has thelength of one segment (i.e., 832 symbols) existing in an ATSC system.

For example, referring to FIG. 21, 2428 bytes of the enhanced data maybe inserted in region A1, 2580 bytes may be inserted in region A2, 2772bytes may be inserted in region A3, 2472 bytes may be inserted in regionA4, and 2772 bytes may be inserted in region A5. Herein, trellisinitialization data or known data, MPEG header, and RS parity are notincluded in the enhanced data. As described above, when region Aincludes a known data sequence at both ends, the receiving system useschannel information that can obtain known data or field synchronizationdata, so as to perform equalization, thereby providing enforcedequalization performance.

Also, region B includes a region located within 8 segments at thebeginning of a field synchronization region within the data group(chronologically placed before region A1) (e.g., region B1), and aregion located within 8 segments behind the very last known datasequence which is inserted in the data group (e.g., region B2). Forexample, 1130 bytes of the enhanced data may be inserted in the regionB1, and 1350 bytes may be inserted in region B2. Similarly, trellisinitialization data or known data, MPEG header, and RS parity are notincluded in the enhanced data. In case of region B, the receiving systemmay perform equalization by using channel information obtained from thefield synchronization section. Alternatively, the receiving system mayalso perform equalization by using channel information that may beobtained from the last known data sequence, thereby enabling the systemto respond to the channel changes.

Region C includes a region located within 30 segments including andpreceding the 9^(th) segment of the field synchronization region(chronologically located before region A) (e.g., region C1), a regionlocated within 12 segments including and following the 9^(th) segment ofthe very last known data sequence within the data group (chronologicallylocated after region A) (e.g., region C2), and a region located in 32segments after the region C2 (e.g., region C3). For example, 1272 bytesof the enhanced data may be inserted in the region C1, 1560 bytes may beinserted in region C2, and 1312 bytes may be inserted in region C3.Similarly, trellis initialization data or known data, MPEG header, andRS parity are not included in the enhanced data. Herein, region C (e.g.,region C1) is located chronologically earlier than (or before) region A.

Since region C (e.g., region C1) is located further apart from the fieldsynchronization region which corresponds to the closest known dataregion, the receiving system may use the channel information obtainedfrom the field synchronization data when performing channelequalization. Alternatively, the receiving system may also use the mostrecent channel information of a previous data group. Furthermore, inregion C (e.g., region C2 and region C3) located before region A, thereceiving system may use the channel information obtained from the lastknown data sequence to perform equalization. However, when the channelsare subject to fast and frequent changes, the equalization may not beperformed perfectly. Therefore, the equalization performance of region Cmay be deteriorated as compared to that of region B.

When it is assumed that the data group is allocated with a plurality ofhierarchically divided regions, as described above, the block processor1113 may encode the enhanced data, which are to be inserted to eachregion based upon the characteristic of each hierarchical region, at adifferent coding rate. For example, the block processor 1113 may encodethe enhanced data, which are to be inserted in regions A1 to A5 ofregion A, at a coding rate of ½. Then, the group formatter 1114 mayinsert the ½-rate encoded enhanced data to regions A1 to A5.

The block processor 1113 may encode the enhanced data, which are to beinserted in regions B1 and B2 of region B, at a coding rate of ¼ havinghigher error correction ability as compared to the ½-coding rate. Then,the group formatter 1114 inserts the ¼-rate coded enhanced data inregion B1 and region B2. Furthermore, the block processor 1113 mayencode the enhanced data, which are to be inserted in regions C1 to C3of region C, at a coding rate of ¼ or a coding rate having higher errorcorrection ability than the ¼ coding rate. Then, the group formatter1114 may either insert the encoded enhanced data to regions C1 to C3, asdescribed above, or leave the data in a reserved region for futureusage.

In addition, the group formatter 1114 also inserts supplemental data,such as signaling information that notifies the overall transmissioninformation, other than the enhanced data in the data group. Also, apartfrom the encoded enhanced data outputted from the block processor 1113,the group formatter 1114 also inserts MPEG header place holders,non-systematic RS parity place holders, main data place holders, whichare related to data deinterleaving in a later process, as shown in FIG.21. Herein, the main data place holders are inserted because theenhanced data bytes and the main data bytes are alternately mixed withone another in regions B and C based upon the input of the datadeinterleaver, as shown in FIG. 21. For example, based upon the dataoutputted after data deinterleaving, the place holder for the MPEGheader may be allocated at the very beginning of each packet.

Furthermore, the group formatter 1114 either inserts known datagenerated in accordance with a pre-determined method or inserts knowndata place holders for inserting the known data in a later process.Additionally, place holders for initializing the trellis encoder 1127are also inserted in the corresponding regions. For example, theinitialization data place holders may be inserted in the beginning ofthe known data sequence. Herein, the size of the enhanced data that canbe inserted in a data group may vary in accordance with the sizes of thetrellis initialization place holders or known data (or known data placeholders) MPEG header place holders, and RS parity place holders.

The output of the group formatter 1114 is inputted to the datadeinterleaver 1115. And, the data deinterleaver 1115 deinterleaves databy performing an inverse process of the data interleaver on the data andplace holders within the data group, which are then outputted to thepacket formatter 1116. More specifically, when the data and placeholders within the data group configured, as shown in FIG. 21, aredeinterleaved by the data deinterleaver 1115, the data group beingoutputted to the packet formatter 1116 is configured to have thestructure shown in FIG. 22.

Among the data deinterleaved and inputted, the packet formatter 1116removes the main data place holder and RS parity place holder that wereallocated for the deinterleaving process from the inputted deinterleaveddata. Thereafter, the remaining portion of the corresponding data isgrouped, and 4 bytes of MPEG header are inserted therein. The 4-byteMPEG header is configured of a 1-byte MPEG synchronization byte added tothe 3-byte MPEG header place holder.

When the group formatter 1114 inserts the known data place holder, thepacket formatter 1116 may either insert actual known data in the knowndata place holder or output the known data place holder without anychange or modification for a replacement insertion in a later process.Afterwards, the packet formatter 1116 divides the data within theabove-described packet-formatted data group into 188-byte unit enhanceddata packets (i.e., MPEG TS packets), which are then provided to thepacket multiplexer 1121. The packet multiplexer 1121 multiplexes the188-byte unit enhanced data packet and main data packet outputted fromthe packet formatter 1116 according to a pre-defined multiplexingmethod. Subsequently, the multiplexed data packets are outputted to thedata randomizer 1122. The multiplexing method may be modified or alteredin accordance with diverse variables of the system design.

As an example of the multiplexing method of the packet multiplexer 1121,the enhanced data burst section and the main data section may beidentified along a time axis (or a chronological axis) and may bealternately repeated. At this point, the enhanced data burst section maytransmit at least one data group, and the main data section may transmitonly the main data. The enhanced data burst section may also transmitthe main data. If the enhanced data are outputted in a burst structure,as described above, the receiving system receiving only the enhanceddata may turn the power on only during the burst section so as toreceive the enhanced data, and may turn the power off during the maindata section in which main data are transmitted, so as to prevent themain data from being received, thereby reducing the power consumption ofthe receiving system.

When the data being inputted correspond to the main data packet, thedata randomizer 1122 performs the same randomizing process of theconventional randomizer. More specifically, the MPEG synchronizationbyte included in the main data packet is discarded and a pseudo randombyte generated from the remaining 187 bytes is used so as to randomizethe data. Thereafter, the randomized data are outputted to the RSencoder/non-systematic RS encoder 1123. However, when the inputted datacorrespond to the enhanced data packet, the MPEG synchronization byte ofthe 4-byte MPEG header included in the enhanced data packet isdiscarded, and data randomizing is performed only on the remaining3-byte MPEG header. Randomizing is not performed on the remainingportion of the enhanced data. Instead, the remaining portion of theenhanced data is outputted to the RS encoder/non-systematic RS encoder1123. This is because the randomizing process has already been performedon the enhanced data by the enhanced data randomizer 1111 in an earlierprocess. Herein, a data randomizing process may or may not be performedon the known data (or known data place holder) and the initializationdata place holder included in the enhanced data packet.

The RS encoder/non-systematic RS encoder 1123 RS-codes the datarandomized by the data randomizer 1122 or the data bypassing the datarandomizer 1122. Then, the RS encoder/non-systematic RS encoder 1123adds a 20-byte RS parity to the coded data, thereby outputting theRS-parity-added data to the data interleaver 1124. At this point, if theinputted data correspond to the main data packet, the RSencoder/non-systematic RS encoder 1123 performs a systematic RS-codingprocess identical to that of the conventional receiving system on theinputted data, thereby adding the 20-byte RS parity at the end of the187-byte data. Alternatively, if the inputted data correspond to theenhanced data packet, the 20 bytes of RS parity gained by performing thenon-systematic RS-coding are respectively inserted in the decided paritybyte places within the enhanced data packet. Herein, the datainterleaver 1124 corresponds to a byte unit convolutional interleaver.The output of the data interleaver 1124 is inputted to the parity bytereplacer 1125 and the non-systematic RS encoder 1126.

Meanwhile, a memory within the trellis encoding module 1127, which ispositioned after the parity byte replacer 1125, should first beinitialized in order to allow the output data of the trellis encodingmodule 1127 so as to become the known data defined based upon anagreement between the receiving system and the transmitting system. Morespecifically, the memory of the trellis encoding module 1127 shouldfirst be initialized before the known data sequence being inputted istrellis-encoded. At this point, the beginning of the known data sequencethat is inputted corresponds to the initialization data place holderinserted by the group formatter 1114 and not the actual known data.Therefore, a process of generating initialization data right before thetrellis-encoding of the known data sequence being inputted and a processof replacing the initialization data place holder of the correspondingtrellis encoding module memory with the newly generated initializationdata are required.

A value of the trellis memory initialization data is decided based uponthe memory status of the trellis encoding module 1127, therebygenerating the trellis memory initialization data accordingly. Due tothe influence of the replace initialization data, a process ofrecalculating the RS parity, thereby replacing the RS parity outputtedfrom the trellis encoding module 1127 with the newly calculated RSparity is required. Accordingly, the non-systematic RS encoder 1126receives the enhanced data packet including the initialization dataplace holder that is to be replaced with the initialization data fromthe data interleaver 1124 and also receives the initialization data fromthe trellis encoding module 1127. Thereafter, among the receivedenhanced data packet, the initialization data place holder is replacedwith the initialization data. Subsequently, the RS parity data added tothe enhanced data packet are removed, Then, a new non-systematic RSparity is calculated and outputted to the parity byte replacer 1125.Accordingly, the parity byte replacer 1125 selects the output of thedata interleaver 1124 as the data within the enhanced data packet, andselects the output of the non-systematic RS encoder 1126 as the RSparity. Thereafter, the parity byte replacer 1125 outputs the selecteddata.

Meanwhile, if the main data packet is inputted, or if the enhanced datapacket that does not include the initialization data place holder thatis to be replaced, the parity byte replacer 1125 selects the data and RSparity outputted from the data interleaver 1124 and directly outputs theselected data to the trellis encoding module 1127 without modification.The trellis encoding module 1127 converts the byte-unit data tosymbol-unit data and 12-way interleaves and trellis-encodes theconverted data, which are then outputted to the frame multiplexer 1128.The frame multiplexer 1128 inserts field synchronization and segmentsynchronization signals in the output of the trellis encoding module1127 and then outputs the processed data to the transmitting unit 1130.Herein, the transmitting unit 1130 includes a pilot inserter 1131, amodulator 1132, and a radio frequency (RF) up-converter 1133. Theoperation of the transmitting unit 1130 is identical to the conventionaltransmitters. Therefore, a detailed description of the same will beomitted for simplicity.

FIG. 23 illustrates a block diagram of a demodulating unit included inthe receiving system according to another embodiment of the presentinvention. Herein, the demodulating unit may effectively process signalstransmitted from the transmitting system shown in FIG. 20. Referring toFIG. 23, the demodulating unit includes a demodulator 2001, a channelequalizer 2002, a known data detector 2003, a block decoder 2004, anenhanced data deformatter 2005, a RS frame decoder 2006, an enhanceddata derandomizer 2007, a data deinterleaver 2008, a RS decoder 2009,and a main data derandomizer 2010. For simplicity, the demodulator 2001,the channel equalizer 2002, the known data detector 2003, the blockdecoder 2004, the enhanced data deformatter 2005, the RS frame decoder2006, and the enhanced data derandomizer 2007 will be referred to as anenhanced data processor. And, the data deinterleaver 2008, the RSdecoder 2009, and the main data derandomizer 2010 will be referred to asa main data processor.

More specifically, the enhanced data including known data and the maindata are received through the tuner and inputted to the demodulator 2001and the known data detector 2003. The demodulator 2001 performsautomatic gain control, carrier wave recovery, and timing recovery onthe data that are being inputted, thereby creating baseband data, whichare then outputted to the equalizer 2002 and the known data detector2003. The equalizer 2002 compensates the distortion within the channelincluded in the demodulated data. Then, the equalizer 2002 outputs thecompensated data to the block decoder 2004.

At this point, the known data detector 2003 detects the known data placeinserted by the transmitting system to the input/output data of thedemodulator 2001 (i.e., data prior to demodulation or data afterdemodulation). Then, along with the position information, the known datadetector 2003 outputs the symbol sequence of the known data generatedfrom the corresponding position to the demodulator 2001 and theequalizer 2002. Additionally, the known data detector 2003 outputsinformation enabling the block decoder 2004 to identify the enhanceddata being additionally encoded by the transmitting system and the maindata that are not additionally encoded to the block decoder 2004.Furthermore, although the connection is not shown in FIG. 23, theinformation detected by the known data detector 2003 may be used in theoverall receiving system and may also be used in the enhanced dataformatter 2005 and the RS frame decoder 2006.

By using the known data symbol sequence when performing the timingrecovery or carrier wave recovery, the demodulating performance of thedemodulator 2001 may be enhanced. Similarly, by using the known data,the channel equalizing performance of the channel equalizer 2002 may beenhanced. Furthermore, by feeding-back the decoding result of the blockdecoder 2004 to the channel equalizer 2002, the channel equalizingperformance may also be enhanced.

The channel equalizer 2002 may perform channel equalization by using aplurality of methods. An example of estimating a channel impulseresponse (CIR) so as to perform channel equalization will be given inthe description of the present invention. Most particularly, an exampleof estimating the CIR in accordance with each region within the datagroup, which is hierarchically divided and transmitted from thetransmitting system, and applying each CIR differently will also bedescribed herein. Furthermore, by using the known data, the place andcontents of which is known in accordance with an agreement between thetransmitting system and the receiving system, and the fieldsynchronization data, so as to estimate the CIR, the present inventionmay be able to perform channel equalization with more stability.

Herein, the data group that is inputted for the equalization process isdivided into regions A to C, as shown in FIG. 21. More specifically, inthe example of the present invention, each region A, B, and C arefurther divided into regions A1 to A5, regions B1 and B2, and regions C1to C3, respectively. Referring to FIG. 21, the CIR that is estimatedfrom the field synchronization data in the data structure is referred toas CIR_FS. Alternatively, the CIRs that are estimated from each of the 5known data sequences existing in region A are sequentially referred toas CIR_N0, CIR_N1, CIR_N2, CIR_N3, and CIR_N4.

As described above, the present invention uses the CIR estimated fromthe field synchronization data and the known data sequences in order toperform channel equalization on data within the data group. At thispoint, each of the estimated CIRs may be directly used in accordancewith the characteristics of each region within the data group.Alternatively, a plurality of the estimated CIRs may also be eitherinterpolated or extrapolated so as to create a new CIR, which is thenused for the channel equalization process.

Herein, when a value F(Q) of a function F(x) at a particular point Q anda value F(S) of the function F(x) at another particular point S areknown, interpolation refers to estimating a function value of a pointwithin the section between points Q and S. Linear interpolationcorresponds to the simplest form among a wide range of interpolationoperations. The linear interpolation described herein is merelyexemplary among a wide range of possible interpolation methods. And,therefore, the present invention is not limited only to the examples setforth herein.

Alternatively, when a value F(Q) of a function F(x) at a particularpoint Q and a value F(S) of the function F(x) at another particularpoint S are known, extrapolation refers to estimating a function valueof a point outside of the section between points Q and S. Linearextrapolation is the simplest form among a wide range of extrapolationoperations. Similarly, the linear extrapolation described herein ismerely exemplary among a wide range of possible extrapolation methods.And, therefore, the present invention is not limited only to theexamples set forth herein.

More specifically, in case of region C1, any one of the CIR_N4 estimatedfrom a previous data group, the CIR_FS estimated from the current datagroup that is to be processed with channel equalization, and a new CIRgenerated by extrapolating the CIR_FS of the current data group and theCIR_N0 may be used to perform channel equalization. Alternatively, incase of region B1, a variety of methods may be applied as described inthe case for region C1. For example, a new CIR created by linearlyextrapolating the CIR_FS estimated from the current data group and theCIR_N0 may be used to perform channel equalization. Also, the CIR_FSestimated from the current data group may also be used to performchannel equalization. Finally, in case of region A1, a new CIR may becreated by interpolating the CIR_FS estimated from the current datagroup and CIR_N0, which is then used to perform channel equalization.Furthermore, any one of the CIR_FS estimated from the current data groupand CIR_N0 may be used to perform channel equalization.

In case of regions A2 to A5, CIR_N(i−1) estimated from the current datagroup and CIR_N(i) may be interpolated to create a new CIR and use thenewly created CIR to perform channel equalization. Also, any one of theCIR_N(i−1) estimated from the current data group and the CIR_N(i) may beused to perform channel equalization. Alternatively, in case of regionsB2, C2, and C3, CIR_N3 and CIR_N4 both estimated from the current datagroup may be extrapolated to create a new CIR, which is then used toperform the channel equalization process. Furthermore, the CIR_N4estimated from the current data group may be used to perform the channelequalization process. Accordingly, an optimum performance may beobtained when performing channel equalization on the data inserted inthe data group. The methods of obtaining the CIRs required forperforming the channel equalization process in each region within thedata group, as described above, are merely examples given to facilitatethe understanding of the present invention. A wider range of methods mayalso be used herein. And, therefore, the present invention will not onlybe limited to the examples given in the description set forth herein.

Meanwhile, if the data being channel equalized and then inputted to theblock decoder 2004 correspond to the enhanced data on which additionalencoding and trellis encoding are both performed by the transmittingsystem, trellis-decoding and additional decoding processes are performedas inverse processes of the transmitting system. Alternatively, if thedata being channel equalized and then inputted to the block decoder 2004correspond to the main data on which additional encoding is notperformed and only trellis-encoding is performed by the transmittingsystem, only the trellis-decoding process is performed. The data groupdecoded by the block decoder 2004 is inputted to the enhanced datadeformatter 2005, and the main data packet is inputted to the datadeinterleaver 2008.

More specifically, if the inputted data correspond to the main data, theblock decoder 2004 performs Viterbi decoding on the inputted data, so asto either output a hard decision value or hard-decide a soft decisionvalue and output the hard-decided result. On the other hand, if theinputted correspond to the enhanced data, the block decoder 2004 outputseither a hard decision value or a soft decision value on the inputtedenhanced data. In other words, if the data inputted to the block decoder2004 correspond to the enhanced data, the block decoder 2004 performs adecoding process on the data encoded by the block processor and thetrellis encoder of the transmitting system. At this point, the output ofthe RS frame encoder included in the pre-processor of the transmittingsystem becomes an external code, and the output of the block processorand the trellis encoder becomes an internal code. In order to showmaximum performance of the external code when decoding such connectioncodes, the decoder of the internal code should output a soft decisionvalue. Therefore, the block decoder 2004 may output a hard decisionvalue on the enhanced data. However, when required, it is morepreferable that the block decoder 2004 outputs a soft decision value.

The present invention may also be used for configuring a reliability mapusing the soft decision value. The reliability map determines andindicates whether a byte corresponding to a group of 8 bits decided bythe code of the soft decision value is reliable. For example, when anabsolute value of the soft decision value exceeds a pre-determinedthreshold value, the value of the bit corresponding to the soft decisionvalue code is determined to be reliable. However, if the absolute valuedoes not exceed the pre-determined threshold value, then the value ofthe corresponding bit is determined to be not reliable. Further, if atleast one bit among the group of 8 bits, which are determined based uponthe soft decision value, is determined to be not reliable, then thereliability map indicates that the entire byte is not reliable. Herein,the process of determining the reliability by 1-bit units is merelyexemplary. The corresponding byte may also be indicated to be notreliable if a plurality of bits (e.g., 4 bits) is determined to be notreliable.

Conversely, when all of the bits are determined to be reliable withinone byte (i.e., when the absolute value of the soft value of all bitsexceeds the pre-determined threshold value), then the reliability mapdetermines and indicates that the corresponding data byte is reliable.Similarly, when more than 4 bits are determined to be reliable withinone data byte, then the reliability map determines and indicates thatthe corresponding data byte is reliable. The estimated numbers aremerely exemplary and do not limit the scope and spirit of the presentinvention. Herein, the reliability map may be used when performing errorcorrection decoding processes.

Meanwhile, the data deinterleaver 2008, the RS decoder 2009, and themain data derandomizer 2010 are blocks required for receiving the maindata. These blocks may not be required in a receiving system structurethat receives only the enhanced data. The data deinterleaver 2008performs an inverse process of the data interleaver of the transmittingsystem. More specifically, the data deinterleaver 2008 deinterleaves themain data being outputted from the block decode 2004 and outputs thedeinterleaved data to the RS decoder 2009. The RS decoder 2009 performssystematic RS decoding on the deinterleaved data and outputs thesystematically decoded data to the main data derandomizer 2010. The maindata derandomizer 2010 receives the data outputted from the RS decoder2009 so as to generate the same pseudo random byte as that of therandomizer in the transmitting system. The main data derandomizer 2010then performs a bitwise exclusive OR (XOR) operation on the generatedpseudo random data byte, thereby inserting the MPEG synchronizationbytes to the beginning of each packet so as to output the data in188-byte main data packet units.

Herein, the format of the data being outputted to the enhanced datadeformatter 2005 from the block decoder 2004 is a data group format. Atthis point, the enhanced data deformatter 2005 already knows thestructure of the input data. Therefore, the enhanced data deformatter2005 identifies the system information including signaling informationand the enhanced data from the data group. Thereafter, the identifiedsignaling information is transmitted to where the system information isrequired, and the enhanced data are outputted to the RS frame decoder2006. The enhanced data deformatter 2005 removes the known data, trellisinitialization data, and MPEG header that were included in the main dataand the data group and also removes the RS parity that was added by theRS encoder/non-systematic RS encoder of the transmitting system.Thereafter, the processed data are outputted to the RS frame decoder2006.

More specifically, the RS frame decoder 2006 receives the RS-coded andCRC-coded enhanced data from the enhanced data deformatter 2005 so as toconfigure the RS frame. The RS frame decoder 2006 performs an inverseprocess of the RS frame encoder included in the transmitting system,thereby correcting the errors within the RS frame. Then, the 1-byte MPEGsynchronization byte, which was removed during the RS frame codingprocess, is added to the error corrected enhanced data packet.Subsequently, the processed data are outputted to the enhanced dataderandomizer 2007. Herein, the enhanced data derandomizer 2007 performsa derandomizing process, which corresponds to an inverse process of theenhanced data randomizer included in the transmitting system, on thereceived enhanced data. Then, by outputting the processed data, theenhanced data transmitted from the transmitting system can be obtained.

According to an embodiment of the present invention, the RS framedecoder 2006 may also be configured as follows. The RS frame decoder2006 may perform a CRC syndrome check on the RS frame, thereby verifyingwhether or not an error has occurred in each row. Subsequently, the CRCchecksum is removed and the presence of an error is indicated on a CRCerror flag corresponding to each row. Then, a RS decoding process isperformed on the RS frame having the CRC checksum removed in a columndirection. At this point, depending upon the number of CRC error flags,a RS erasure decoding process may be performed. More specifically, bychecking the CRC error flags corresponding to each row within the RSframe, the number of CRC error flags may be determined whether it isgreater or smaller than the maximum number of errors, when RS decodingthe number of rows with errors (or erroneous rows) in the columndirection. Herein, the maximum number of errors corresponds to thenumber of parity bytes inserted during the RS decoding process. As anexample of the present invention, it is assumed that 48 parity bytes areadded to each column.

If the number of rows with CRC errors is equal to or smaller than themaximum number of errors (e.g., 48), which may be corrected by the RSerasure decoding process, the RS erasure decoding process is performedon the RS frame in the column direction. Thereafter, the 48 bytes ofparity data that were added at the end of each column are removed.However, if the number of rows with CRC errors is greater than themaximum number of errors (e.g., 48), which may be corrected by the RSerasure decoding process, the RS erasure decoding process cannot beperformed. In this case, the error may be corrected by performing ageneral RS decoding process.

As another embodiment of the present invention, the error correctionability may be enhanced by using the reliability map created whenconfiguring the RS frame from the soft decision value. Morespecifically, the RS frame decoder 2006 compares the absolute value ofthe soft decision value obtained from the block decoder 2004 to thepre-determined threshold value so as to determine the reliability of thebit values that are decided by the code of the corresponding softdecision value. Then, 8 bits are grouped to configure a byte. Then, thereliability information of the corresponding byte is indicated on thereliability map. Therefore, even if a specific row is determined to haveCRC errors as a result of the CRC syndrome checking process of thecorresponding row, it is not assumed that all of the data bytes includedin the corresponding row have error. Instead, only the data bytes thatare determined to be not reliable, after referring to the reliabilityinformation on the reliability map, are set to have errors. In otherwords, regardless of the presence of CRC errors in the correspondingrow, only the data bytes that are determined to be not reliable (orunreliable) by the reliability map are set as erasure points.

Thereafter, if the number of erasure points for each column is equal toor smaller than the maximum number of errors (e.g., 48), the RS erasuredecoding process is performed on the corresponding the column.Conversely, if the number of erasure points is greater than the maximumnumber of errors (e.g., 48), which may be corrected by the RS erasuredecoding process, a general decoding process is performed on thecorresponding column. In other words, if the number of rows having CRCerrors is greater than the maximum number of errors (e.g., 48), whichmay be corrected by the RS erasure decoding process, either a RS erasuredecoding process or a general RS decoding process is performed on aparticular column in accordance with the number of erasure point withinthe corresponding column, wherein the number is decided based upon thereliability information on the reliability map. When the above-describedprocess is performed, the error correction decoding process is performedin the direction of all of the columns included in the RS frame.Thereafter, the 48 bytes of parity data added to the end of each columnare removed.

FIG. 24 illustrates a block diagram showing the structure of a digitalbroadcast receiving system according to an embodiment of the presentinvention. Referring to FIG. 24, the digital broadcast receiving systemincludes a tuner 3001, a demodulating unit 3002, a demultiplexer 3003,an audio decoder 3004, a video decoder 3005, a native TV applicationmanager 3006, a channel manager 3007, a channel map 3008, a first memory3009, a data decoder 3010, a second memory 3011, a system manager 3012,a data broadcasting application manager 3013, a storage controller 3014,and a third memory 3015. Herein, the third memory 3015 is a mass storagedevice, such as a hard disk drive (HDD) or a memory chip. The tuner 3001tunes a frequency of a specific channel through any one of an antenna,cable, and satellite. Then, the tuner 3001 down-converts the tunedfrequency to an intermediate frequency (IF), which is then outputted tothe demodulating unit 3002. At this point, the tuner 3001 is controlledby the channel manager 3007. Additionally, the result and strength ofthe broadcast signal of the tuned channel are also reported to thechannel manager 3007. The data that are being received by the frequencyof the tuned specific channel include main data, enhanced data, andtable data for decoding the main data and enhanced data.

In the embodiment of the present invention, examples of the enhanceddata may include data provided for data service, such as Javaapplication data, HTML application data, XML data, and so on. The dataprovided for such data services may correspond either to a Java classfile for the Java application, or to a directory file designatingpositions (or locations) of such files. Furthermore, such data may alsocorrespond to an audio file and/or a video file used in eachapplication. The data services may include weather forecast services,traffic information services, stock information services, servicesproviding information quiz programs providing audience participationservices, real time poll, user interactive education programs, gamingservices, services providing information on soap opera (or TV series)synopsis, characters, original sound track, filing sites, servicesproviding information on past sports matches, profiles andaccomplishments of sports players, product information and productordering services, services providing information on broadcast programsby media type, airing time, subject, and so on. The types of dataservices described above are only exemplary and are not limited only tothe examples given herein. Furthermore, depending upon the embodiment ofthe present invention, the enhanced data may correspond to meta data.For example, the meta data use the XML application so as to betransmitted through a DSM-CC protocol.

The demodulating unit 3002 performs demodulation and channelequalization on the signal being outputted from the tuner 3001, therebyidentifying the main data and the enhanced data. Thereafter, theidentified main data and enhanced data are outputted in TS packet units.Examples of the demodulating unit 3002 are shown in FIG. 16 and FIG. 23.The demodulating unit shown in FIG. 16 and FIG. 23 is merely exemplaryand the scope of the present invention is not limited to the examplesset forth herein. In the embodiment given as an example of the presentinvention, only the enhanced data packet outputted from the demodulatingunit 3002 is inputted to the demultiplexer 3003. In this case, the maindata packet is inputted to another demultiplexer (not shown) thatprocesses main data packets. Herein, the storage controller 3014 is alsoconnected to the other demultiplexer in order to store the main dataafter processing the main data packets. The demultiplexer of the presentinvention may also be designed to process both enhanced data packets andmain data packets in a single demultiplexer.

The storage controller 3014 is interfaced with the demultiplexer so asto control instant recording, reserved (or pre-programmed) recording,time shift, and so on of the enhanced data and/or main data. Forexample, when one of instant recording, reserved (or pre-programmed)recording, and time shift is set and programmed in the receiving system(or receiver) shown in FIG. 24, the corresponding enhanced data and/ormain data that are inputted to the demultiplexer are stored in the thirdmemory 3015 in accordance with the control of the storage controller3014. The third memory 3015 may be described as a temporary storage areaand/or a permanent storage area. Herein, the temporary storage area isused for the time shifting function, and the permanent storage area isused for a permanent storage of data according to the user's choice (ordecision).

When the data stored in the third memory 3015 need to be reproduced (orplayed), the storage controller 3014 reads the corresponding data storedin the third memory 3015 and outputs the read data to the correspondingdemultiplexer (e.g., the enhanced data are outputted to thedemultiplexer 3003 shown in FIG. 24). At this point, according to theembodiment of the present invention, since the storage capacity of thethird memory 3015 is limited, the compression encoded enhanced dataand/or main data that are being inputted are directly stored in thethird memory 3015 without any modification for the efficiency of thestorage capacity. In this case, depending upon the reproduction (orreading) command, the data read from the third memory 3015 pass troughthe demultiplexer so as to be inputted to the corresponding decoder,thereby being restored to the initial state.

The storage controller 3014 may control the reproduction (or play),fast-forward, rewind, slow motion, instant replay functions of the datathat are already stored in the third memory 3015 or presently beingbuffered. Herein, the instant replay function corresponds to repeatedlyviewing scenes that the viewer (or user) wishes to view once again. Theinstant replay function may be performed on stored data and also on datathat are currently being received in real time by associating theinstant replay function with the time shift function. If the data beinginputted correspond to the analog format, for example, if thetransmission mode is NTSC, PAL, and so on, the storage controller 3014compression encodes the inputted data and stored the compression-encodeddata to the third memory 3015. In order to do so, the storage controller3014 may include an encoder, wherein the encoder may be embodied as oneof software, middleware, and hardware. Herein, an MPEG encoder may beused as the encoder according to an embodiment of the present invention.The encoder may also be provided outside of the storage controller 3014.

Meanwhile, in order to prevent illegal duplication (or copies) of theinput data being stored in the third memory 3015, the storage controller3014 scrambles the input data and stores the scrambled data in the thirdmemory 3015. Accordingly, the storage controller 3014 may include ascramble algorithm for scrambling the data stored in the third memory3015 and a descramble algorithm for descrambling the data read from thethird memory 3015. Herein, the definition of scramble includesencryption, and the definition of descramble includes decryption. Thescramble method may include using an arbitrary key (e.g., control word)to modify a desired set of data, and also a method of mixing signals.

Meanwhile, the demultiplexer 3003 receives the real-time data outputtedfrom the demodulating unit 3002 or the data read from the third memory3015 and demultiplexes the received data. In the example given in thepresent invention, the demultiplexer 3003 performs demultiplexing on theenhanced data packet. Therefore, in the present invention, the receivingand processing of the enhanced data will be described in detail. Itshould also be noted that a detailed description of the processing ofthe main data will be omitted for simplicity starting from thedescription of the demultiplexer 3003 and the subsequent elements.

The demultiplexer 3003 demultiplexes enhanced data and program specificinformation/program and system information protocol (PSI/PSIP) tablesfrom the enhanced data packet inputted in accordance with the control ofthe data decoder 3010. Thereafter, the demultiplexed enhanced data andPSI/PSIP tables are outputted to the data decoder 3010 in a sectionformat. In order to extract the enhanced data from the channel throughwhich enhanced data are transmitted and to decode the extracted enhanceddata, system information is required. Such system information may alsobe referred to as service information. The system information mayinclude channel information, event information, etc. In the embodimentof the present invention, the PSI/PSIP tables are applied as the systeminformation. However, the present invention is not limited to theexample set forth herein. More specifically, regardless of the name, anyprotocol transmitting system information in a table format may beapplied in the present invention.

The PSI table is an MPEG-2 system standard defined for identifying thechannels and the programs. The PSIP table is an advanced televisionsystems committee (ATSC) standard that can identify the channels and theprograms. The PSI table may include a program association table (PAT), aconditional access table (CAT), a program map table (PMT), and a networkinformation table (NIT). Herein, the PAT corresponds to specialinformation that is transmitted by a data packet having a PID of ‘0’.The PAT transmits PID information of the PMT and PID information of theNIT corresponding to each program. The CAT transmits information on apaid broadcast system used by the transmitting system. The PMT transmitsPID information of a transport stream (TS) packet, in which programidentification numbers and individual bit sequences of video and audiodata configuring the corresponding program are transmitted, and the PIDinformation, in which PCR is transmitted. The NIT transmits informationof the actual transmission network.

The PSIP table may include a virtual channel table (VCT), a system timetable (STT), a rating region table (RRT), an extended text table (ETT),a direct channel change table (DCCT), an event information table (EIT),and a master guide table (MGT). The VCT transmits information on virtualchannels, such as channel information for selecting channels andinformation such as packet identification (PID) numbers for receivingthe audio and/or video data. More specifically, when the VCT is parsed,the PID of the audio/video data of the broadcast program may be known.Herein, the corresponding audio/video data are transmitted within thechannel along with the channel name and the channel number. The STTtransmits information on the current data and timing information. TheRRT transmits information on region and consultation organs for programratings. The ETT transmits additional description of a specific channeland broadcast program. The EIT transmits information on virtual channelevents (e.g., program title, program start time, etc.). The DCCT/DCCSCTtransmits information associated with automatic (or direct) channelchange. And, the MGT transmits the versions and PID information of theabove-mentioned tables included in the PSIP.

Each of the above-described tables included in the PSI/PSIP isconfigured of a basic unit referred to as a “section”, and a combinationof one or more sections forms a table. For example, the VCT may bedivided into 256 sections. Herein, one section may include a pluralityof virtual channel information. However, a single set of virtual channelinformation is not divided into two or more sections. At this point, thereceiving system may parse and decode the data for the data service thatare transmitting by using only the tables included in the PSI, or onlythe tables included in the PISP, or a combination of tables included inboth the PSI and the PSIP. In order to parse and decode the data for thedata service, at least one of the PAT and PMT included in the PSI, andthe VCT included in the PSIP is required. For example, the PAT mayinclude the system information for transmitting the data correspondingto the data service, and the PID of the PMT corresponding to the dataservice data (or program number). The PMT may include the PID of the TSpacket used for transmitting the data service data. The VCT may includeinformation on the virtual channel for transmitting the data servicedata, and the PID of the TS packet for transmitting the data servicedata.

Meanwhile, depending upon the embodiment of the present invention, aDVB-SI may be applied instead of the PSIP. The DVB-SI may include anetwork information table (NIT), a service description table (SDT), anevent information table (EIT), and a time and data table (TDT). TheDVB-SI may be used in combination with the above-described PSI. Herein,the NIT divides the services corresponding to particular networkproviders by specific groups. The NIT includes all tuning informationthat are used during the IRD set-up. The NIT may be used for informingor notifying any change in the tuning information. The SDT includes theservice name and different parameters associated with each servicecorresponding to a particular MPEG multiplex. The EIT is used fortransmitting information associated with all events occurring in theMPEG multiplex. The EIT includes information on the current transmissionand also includes information selectively containing differenttransmission streams that may be received by the IRD. And, the TDT isused for updating the clock included in the IRD.

Furthermore, three selective SI tables (i.e., a bouquet associate table(BAT), a running status table (RST), and a stuffing table (ST)) may alsobe included. More specifically, the bouquet associate table (BAT)provides a service grouping method enabling the IRD to provide servicesto the viewers. Each specific service may belong to at least one‘bouquet’ unit. A running status table (RST) section is used forpromptly and instantly updating at least one event execution status. Theexecution status section is transmitted only once at the changing pointof the event status. Other SI tables are generally transmitted severaltimes. The stuffing table (ST) may be used for replacing or discarding asubsidiary table or the entire SI tables.

In the present invention, the enhanced data included in the payloadwithin the TS packet consist of a digital storage media-command andcontrol (DSM-CC) section format. However, the TS packet including thedata service data may correspond either to a packetized elementarystream (PES) type or to a section type. More specifically, either thePES type data service data configure the TS packet, or the section typedata service data configure the TS packet. The TS packet configured ofthe section type data will be given as the example of the presentinvention. At this point, the data service data are includes in thedigital storage media-command and control (DSM-CC) section. Herein, theDSM-CC section is then configured of a 188-byte unit TS packet.

Furthermore, the packet identification of the TS packet configuring theDSM-CC section is included in a data service table (DST). Whentransmitting the DST, ‘0x95’ is assigned as the value of a stream_typefield included in the service location descriptor of the PMT or the VCT.More specifically, when the PMT or VCT stream_type field value is‘0x95’, the receiving system may acknowledge that data broadcastingincluding enhanced data (i.e., the enhanced data) is being received. Atthis point, the enhanced data may be transmitted by a data carouselmethod. The data carousel method corresponds to repeatedly transmittingidentical data on a regular basis.

At this point, according to the control of the data decoder 3010, thedemultiplexer 3003 performs section filtering, thereby discardingrepetitive sections and outputting only the non-repetitive sections tothe data decoder 3010. The demultiplexer 3003 may also output only thesections configuring desired tables (e.g., VCT) to the data decoder 3010by section filtering. Herein, the VCT may include a specific descriptorfor the enhanced data. However, the present invention does not excludethe possibilities of the enhanced data being included in other tables,such as the PMT. The section filtering method may include a method ofverifying the PID of a table defined by the MGT, such as the VCT, priorto performing the section filtering process. Alternatively, the sectionfiltering method may also include a method of directly performing thesection filtering process without verifying the MGT, when the VCTincludes a fixed PID (i.e., a base PID). At this point, thedemultiplexer 3003 performs the section filtering process by referringto a table_id field, a version_number field, a section_number field,etc.

As described above, the method of defining the PID of the VCT broadlyincludes two different methods. Herein, the PID of the VCT is a packetidentifier required for identifying the VCT from other tables. The firstmethod consists of setting the PID of the VCT so that it is dependent tothe MGT. In this case, the receiving system cannot directly verify theVCT among the many PSI and/or PSIP tables. Instead, the receiving systemmust check the PID defined in the MGT in order to read the VCT. Herein,the MGT defines the PID, size, version number, and so on, of diversetables. The second method consists of setting the PID of the VCT so thatthe PID is given a base PID value (or a fixed PID value), thereby beingindependent from the MGT. In this case, unlike in the first method, theVCT according to the present invention may be identified without havingto verify every single PID included in the MGT. Evidently, an agreementon the base PID must be previously made between the transmitting systemand the receiving system.

Meanwhile, in the embodiment of the present invention, the demultiplexer3003 may output only an application information table (AIT) to the datadecoder 3010 by section filtering. The AIT includes information on anapplication being operated in the receiving system for the data service.The AIT may also be referred to as an XAIT, and an AMT. Therefore, anytable including application information may correspond to the followingdescription. When the AIT is transmitted, a value of ‘0x05’ may beassigned to a stream_type field of the PMT. The AIT may includeapplication information, such as application name, application version,application priority, application ID, application status (i.e.,auto-start, user-specific settings, kill, etc.), application type (i.e.,Java or HTML), position (or location) of stream including applicationclass and data files, application platform directory, and location ofapplication icon.

In the method for detecting application information for the data serviceby using the AIT, component_tag, original_network_id,transport_stream_id, and service_id fields may be used for detecting theapplication information. The component_tag field designates anelementary stream carrying a DSI of a corresponding object carousel. Theoriginal_network_id field indicates a DVB-SI original_network_id of theTS providing transport connection. The transport_stream_id fieldindicates the MPEG TS of the TS providing transport connection, and theservice_id field indicates the DVB-SI of the service providing transportconnection. Information on a specific channel may be obtained by usingthe original_network_id field, the transport_stream_id field, and theservice_id field. The data service data, such as the application data,detected by using the above-described method may be stored in the secondmemory 3011 by the data decoder 3010.

The data decoder 3010 parses the DSM-CC section configuring thedemultiplexed enhanced data. Then, the enhanced data corresponding tothe parsed result are stored as a database in the second memory 3011.The data decoder 3010 groups a plurality of sections having the sametable identification (table_id) so as to configure a table, which isthen parsed. Thereafter, the parsed result is stored as a database inthe second memory 3011. At this point, by parsing data and/or sections,the data decoder 3010 reads all of the remaining actual section datathat are not section-filtered by the demultiplexer 3003. Then, the datadecoder 3010 stores the read data to the second memory 3011. The secondmemory 3011 corresponds to a table and data carousel database storingsystem information parsed from tables and enhanced data parsed from theDSM-CC section. Herein, a table_id field, a section_number field, and alast_section_number field included in the table may be used to indicatewhether the corresponding table is configured of a single section or aplurality of sections. For example, TS packets having the PID of the VCTare grouped to form a section, and sections having table identifiersallocated to the VCT are grouped to form the VCT.

When the VCT is parsed, information on the virtual channel to whichenhanced data are transmitted may be obtained. The obtained applicationidentification information, service component identificationinformation, and service information corresponding to the data servicemay either be stored in the second memory 3011 or be outputted to thedata broadcasting application manager 3013. In addition, reference maybe made to the application identification information, service componentidentification information, and service information in order to decodethe data service data. Alternatively, such information may also preparethe operation of the application program for the data service.Furthermore, the data decoder 3010 controls the demultiplexing of thesystem information table, which corresponds to the information tableassociated with the channel and events. Thereafter, an A.V PID list maybe transmitted to the channel manager 3007.

The channel manager 3007 may refer to the channel map 3008 in order totransmit a request for receiving system-related information data to thedata decoder 3010, thereby receiving the corresponding result. Inaddition, the channel manager 3007 may also control the channel tuningof the tuner 3001. Furthermore, the channel manager 3007 may directlycontrol the demultiplexer 3003, so as to set up the A/V PID, therebycontrolling the audio decoder 3004 and the video decoder 3005. The audiodecoder 3004 and the video decoder 3005 may respectively decode andoutput the audio data and video data demultiplexed from the main datapacket. Alternatively, the audio decoder 3004 and the video decoder 3005may respectively decode and output the audio data and video datademultiplexed from the enhanced data packet. Meanwhile, when theenhanced data include data service data, and also audio data and videodata, it is apparent that the audio data and video data demultiplexed bythe demultiplexer 3003 are respectively decoded by the audio decoder3004 and the video decoder 3005. For example, an audio-coding (AC)-3decoding algorithm may be applied to the audio decoder 3004, and aMPEG-2 decoding algorithm may be applied to the video decoder 3005.

Meanwhile, the native TV application manager 3006 operates a nativeapplication program stored in the first memory 3009, thereby performinggeneral functions such as channel change. The native application programrefers to software stored in the receiving system upon shipping of theproduct. More specifically, when a user request (or command) istransmitted to the receiving system through a user interface (UI), thenative TV application manger 3006 displays the user request on a screenthrough a graphic user interface (GUI), thereby responding to the user'srequest. The user interface receives the user request through an inputdevice, such as a remote controller, a key pad, a jog controller, an atouch-screen provided on the screen, and then outputs the received userrequest to the native TV application manager 3006 and the databroadcasting application manager 3013. Furthermore, the native TVapplication manager 3006 controls the channel manager 3007, therebycontrolling channel-associated, such as the management of the channelmap 3008, and controlling the data decoder 3010. The native TVapplication manager 3006 also controls the GUI of the overall receivingsystem, thereby storing the user request and status of the receivingsystem in the first memory 3009 and restoring the stored information.

The channel manager 3007 controls the tuner 3001 and the data decoder3010, so as to managing the channel map 3008 so that it can respond tothe channel request made by the user. More specifically, channel manager3007 sends a request to the data decoder 3010 so that the tablesassociated with the channels that are to be tuned are parsed. Theresults of the parsed tables are reported to the channel manager 3007 bythe data decoder 3010. Thereafter, based on the parsed results, thechannel manager 3007 updates the channel map 3008 and sets up a PID inthe demultiplexer 3003 for demultiplexing the tables associated with thedata service data from the enhanced data.

The system manager 3012 controls the booting of the receiving system byturning the power on or off. Then, the system manager 3012 stores ROMimages (including downloaded software images) in the first memory 3009.More specifically, the first memory 3009 stores management programs suchas operating system (OS) programs required for managing the receivingsystem and also application program executing data service functions.The application program is a program processing the data service datastored in the second memory 3011 so as to provide the user with the dataservice. If the data service data are stored in the second memory 3011,the corresponding data service data are processed by the above-describedapplication program or by other application programs, thereby beingprovided to the user. The management program and application programstored in the first memory 3009 may be updated or corrected to a newlydownloaded program. Furthermore, the storage of the stored managementprogram and application program is maintained without being deleted evenif the power of the system is shut down. Therefore, when the power issupplied the programs may be executed without having to be newlydownloaded once again.

The application program for providing data service according to thepresent invention may either be initially stored in the first memory3009 upon the shipping of the receiving system, or be stored in thefirst 3009 after being downloaded. The application program for the dataservice (i.e., the data service providing application program) stored inthe first memory 3009 may also be deleted, updated, and corrected.Furthermore, the data service providing application program may bedownloaded and executed along with the data service data each time thedata service data are being received.

When a data service request is transmitted through the user interface,the data broadcasting application manager 3013 operates thecorresponding application program stored in the first memory 3009 so asto process the requested data, thereby providing the user with therequested data service. And, in order to provide such data service, thedata broadcasting application manager 3013 supports the graphic userinterface (GUI). Herein, the data service may be provided in the form oftext (or short message service (SMS)), voice message, still image, andmoving image. The data broadcasting application manager 3013 may beprovided with a platform for executing the application program stored inthe first memory 3009. The platform may be, for example, a Java virtualmachine for executing the Java program. Hereinafter, an example of thedata broadcasting application manager 3013 executing the data serviceproviding application program stored in the first memory 3009, so as toprocess the data service data stored in the second memory 3011, therebyproviding the user with the corresponding data service will now bedescribed in detail.

Assuming that the data service corresponds to a traffic informationservice, the data service according to the present invention is providedto the user of a receiving system that is not equipped with anelectronic map and/or a GPS system in the form of at least one of a text(or short message service (SMS)), a voice message, a graphic message, astill image, and a moving image. In this case, is a GPS module ismounted on the receiving system shown in FIG. 24, the GPS modulereceives satellite signals transmitted from a plurality of low earthorbit satellites and extracts the current position (or location)information (e.g., longitude, latitude, altitude), thereby outputtingthe extracted information to the data broadcasting application manager3013.

At this point, it is assumed that the electronic map includinginformation on each link and nod and other diverse graphic informationare stored in one of the second memory 3011, the first memory 3009, andanother memory that is not shown. More specifically, according to therequest made by the data broadcasting application manager 3013, the dataservice data stored in the second memory 3011 are read and inputted tothe data broadcasting application manager 3013. The data broadcastingapplication manager 3013 translates (or deciphers) the data service dataread from the second memory 3011, thereby extracting the necessaryinformation according to the contents of the message and/or a controlsignal.

FIG. 25 illustrates a block diagram showing the structure of a digitalbroadcast (or television) receiving system according to anotherembodiment of the present invention. Referring to FIG. 25, the digitalbroadcast receiving system includes a tuner 4001, a demodulating unit4002, a demultiplexer 4003, a first descrambler 4004, an audio decoder4005, a video decoder 4006, a second descrambler 4007, an authenticationunit 4008, a native TV application manager 4009, a channel manager 4010,a channel map 4011, a first memory 4012, a data decoder 4013, a secondmemory 4014, a system manager 4015, a data broadcasting applicationmanager 4016, a storage controller 4017, a third memory 4018, and atelecommunication module 4019. Herein, the third memory 4018 is a massstorage device, such as a hard disk drive (HDD) or a memory chip. Also,during the description of the digital broadcast (or television or DTV)receiving system shown in FIG. 25, the components that are identical tothose of the digital broadcast receiving system of FIG. 24 will beomitted for simplicity.

As described above, in order to provide services for preventing illegalduplication (or copies) or illegal viewing of the enhanced data and/ormain data that are transmitted by using a broadcast network, and toprovide paid broadcast services, the transmitting system may generallyscramble and transmit the broadcast contents. Therefore, the receivingsystem needs to descramble the scrambled broadcast contents in order toprovide the user with the proper broadcast contents. Furthermore, thereceiving system may generally be processed with an authenticationprocess with an authentication means before the descrambling process.Hereinafter, the receiving system including an authentication means anda descrambling means according to an embodiment of the present inventionwill now be described in detail.

According to the present invention, the receiving system may be providedwith a descrambling means receiving scrambled broadcasting contents andan authentication means authenticating (or verifying) whether thereceiving system is entitled to receive the descrambled contents.Hereinafter, the descrambling means will be referred to as first andsecond descramblers 4004 and 4007, and the authentication means will bereferred to as an authentication unit 4008. Such naming of thecorresponding components is merely exemplary and is not limited to theterms suggested in the description of the present invention. Forexample, the units may also be referred to as a decryptor. Although FIG.25 illustrates an example of the descramblers 4004 and 4007 and theauthentication unit 4008 being provided inside the receiving system,each of the descramblers 4004 and 4007 and the authentication unit 4008may also be separately provided in an internal or external module.Herein, the module may include a slot type, such as a SD or CF memory, amemory stick type, a USB type, and so on, and may be detachably fixed tothe receiving system.

As described above, when the authentication process is performedsuccessfully by the authentication unit 4008, the scrambled broadcastingcontents are descrambled by the descramblers 4004 and 4007, therebybeing provided to the user. At this point, a variety of theauthentication method and descrambling method may be used herein.However, an agreement on each corresponding method should be madebetween the receiving system and the transmitting system. Hereinafter,the authentication and descrambling methods will now be described, andthe description of identical components or process steps will be omittedfor simplicity.

The receiving system including the authentication unit 4008 and thedescramblers 4004 and 4007 will now be described in detail. Thereceiving system receives the scrambled broadcasting contents throughthe tuner 4001 and the demodulating unit 4002. Then, the system manager4015 decides whether the received broadcasting contents have beenscrambled. Herein, the demodulating unit 4002 may be included as ademodulating means according to embodiments of the present invention asdescribed in FIG. 16 and FIG. 23. However, the present invention is notlimited to the examples given in the description set forth herein. Ifthe system manager 4015 decides that the received broadcasting contentshave been scrambled, then the system manager 4015 controls the system tooperate the authentication unit 4008. As described above, theauthentication unit 4008 performs an authentication process in order todecide whether the receiving system according to the present inventioncorresponds to a legitimate host entitled to receive the paidbroadcasting service. Herein, the authentication process may vary inaccordance with the authentication methods.

For example, the authentication unit 4008 may perform the authenticationprocess by comparing an IP address of an IP datagram within the receivedbroadcasting contents with a specific address of a corresponding host.At this point, the specific address of the corresponding receivingsystem (or host) may be a MAC address. More specifically, theauthentication unit 4008 may extract the IP address from thedecapsulated IP datagram, thereby obtaining the receiving systeminformation that is mapped with the IP address. At this point, thereceiving system should be provided, in advance, with information (e.g.,a table format) that can map the IP address and the receiving systeminformation. Accordingly, the authentication unit 4008 performs theauthentication process by determining the conformity between the addressof the corresponding receiving system and the system information of thereceiving system that is mapped with the IP address. In other words, ifthe authentication unit 4008 determines that the two types ofinformation conform to one another, then the authentication unit 4008determines that the receiving system is entitled to receive thecorresponding broadcasting contents.

In another example, standardized identification information is definedin advance by the receiving system and the transmitting system. Then,the identification information of the receiving system requesting thepaid broadcasting service is transmitted by the transmitting system.Thereafter, the receiving system determines whether the receivedidentification information conforms with its own unique identificationnumber, so as to perform the authentication process. More specifically,the transmitting system creates a database for storing theidentification information (or number) of the receiving systemrequesting the paid broadcasting service. Then, if the correspondingbroadcasting contents are scrambled, the transmitting system includesthe identification information in the EMM, which is then transmitted tothe receiving system.

If the corresponding broadcasting contents are scrambled, messages(e.g., entitlement control message (ECM), entitlement management message(EMM)), such as the CAS information, mode information, message positioninformation, that are applied to the scrambling of the broadcastingcontents are transmitted through a corresponding data header or antherdata packet. The ECM may include a control word (CW) used for scramblingthe broadcasting contents. At this point, the control word may beencoded with an authentication key. The EMM may include anauthentication key and entitlement information of the correspondingdata. Herein, the authentication key may be encoded with a receivingsystem specific distribution key. In other words, assuming that theenhanced data are scrambled by using the control word, and that theauthentication information and the descrambling information aretransmitted from the transmitting system, the transmitting systemencodes the CW with the authentication key and, then, includes theencoded CW in the entitlement control message (ECM), which is thentransmitted to the receiving system. Furthermore, the transmittingsystem includes the authentication key used for encoding the CW and theentitlement to receive data (or services) of the receiving system (i.e.,a standardized serial number of the receiving system that is entitled toreceive the corresponding broadcasting service or data) in theentitlement management message (EMM), which is then transmitted to thereceiving system.

Accordingly, the authentication unit 4008 of the receiving systemextracts the identification information of the receiving system and theidentification information included in the EMM of the broadcastingservice that is being received. Then, the authentication unit 4008determines whether the identification information conform to each other,so as to perform the authentication process. More specifically, if theauthentication unit 4008 determines that the information conform to eachother, then the authentication unit 4008 eventually determines that thereceiving system is entitled to receive the request broadcastingservice.

In yet another example, the authentication unit 4008 of the receivingsystem may be detachably fixed to an external module. In this case, thereceiving system is interfaced with the external module through a commoninterface (CI). In other words, the external module may receive the datascrambled by the receiving system through the common interface, therebyperforming the descrambling process of the received data. Alternatively,the external module may also transmit only the information required forthe descrambling process to the receiving system. The common interfaceis configured on a physical layer and at least one protocol layer.Herein, in consideration of any possible expansion of the protocol layerin a later process, the corresponding protocol layer may be configuredto have at least one layer that can each provide an independentfunction.

The external module may either consist of a memory or card havinginformation on the key used for the scrambling process and otherauthentication information but not including any descrambling function,or consist of a card having the abovementioned key information andauthentication information and including the descrambling function. Boththe receiving system and the external module should be authenticated inorder to provide the user with the paid broadcasting service provided(or transmitted) from the transmitting system. Therefore, thetransmitting system can only provide the corresponding paid broadcastingservice to the authenticated pair of receiving system and externalmodule.

Additionally, an authentication process should also be performed betweenthe receiving system and the external module through the commoninterface. More specifically, the module may communicate with the systemmanager 4015 included in the receiving system through the commoninterface, thereby authenticating the receiving system. Alternatively,the receiving system may authenticate the module through the commoninterface. Furthermore, during the authentication process, the modulemay extract the unique ID of the receiving system and its own unique IDand transmit the extracted IDs to the transmitting system. Thus, thetransmitting system may use the transmitted ID values as informationdetermining whether to start the requested service or as paymentinformation. Whenever necessary, the system manager 4015 transmits thepayment information to the remote transmitting system through thetelecommunication module 4019.

The authentication unit 4008 authenticates the corresponding receivingsystem and/or the external module. Then, if the authentication processis successfully completed, the authentication unit 4008 certifies thecorresponding receiving system and/or the external module as alegitimate system and/or module entitled to receive the requested paidbroadcasting service. In addition, the authentication unit 4008 may alsoreceive authentication-associated information from a mobiletelecommunications service provider to which the user of the receivingsystem is subscribed, instead of the transmitting system providing therequested broadcasting service. In this case, theauthentication-association information may either be scrambled by thetransmitting system providing the broadcasting service and, then,transmitted to the user through the mobile telecommunications serviceprovider, or be directly scrambled and transmitted by the mobiletelecommunications service provider. Once the authentication process issuccessfully completed by the authentication unit 4008, the receivingsystem may descramble the scrambled broadcasting contents received fromthe transmitting system. At this point, the descrambling process isperformed by the first and second descramblers 4004 and 4007. Herein,the first and second descramblers 4004 and 4007 may be included in aninternal module or an external module of the receiving system.

The receiving system is also provided with a common interface forcommunicating with the external module including the first and seconddescramblers 4004 and 4007, so as to perform the descrambling process.More specifically, the first and second descramblers 4004 and 4007 maybe included in the module or in the receiving system in the form ofhardware, middleware or software. Herein, the descramblers 4004 and 4007may be included in any one of or both of the module and the receivingsystem. If the first and second descramblers 4004 and 4007 are providedinside the receiving system, it is advantageous to have the transmittingsystem (i.e., at least any one of a service provider and a broadcaststation) scramble the corresponding data using the same scramblingmethod.

Alternatively, if the first and second descramblers 4004 and 4007 areprovided in the external module, it is advantageous to have eachtransmitting system scramble the corresponding data using differentscrambling methods. In this case, the receiving system is not requiredto be provided with the descrambling algorithm corresponding to eachtransmitting system. Therefore, the structure and size of receivingsystem may be simplified and more compact. Accordingly, in this case,the external module itself may be able to provide CA functions, whichare uniquely and only provided by each transmitting systems, andfunctions related to each service that is to be provided to the user.The common interface enables the various external modules and the systemmanager 4015, which is included in the receiving system, to communicatewith one another by a single communication method. Furthermore, sincethe receiving system may be operated by being connected with at leastone or more modules providing different services, the receiving systemmay be connected to a plurality of modules and controllers.

In order to maintain successful communication between the receivingsystem and the external module, the common interface protocol includes afunction of periodically checking the status of the oppositecorrespondent. By using this function, the receiving system and theexternal module is capable of managing the status of each oppositecorrespondent. This function also reports the user or the transmittingsystem of any malfunction that may occur in any one of the receivingsystem and the external module and attempts the recovery of themalfunction.

In yet another example, the authentication process may be performedthrough software. More specifically, when a memory card having CASsoftware downloaded, for example, and stored therein in advanced isinserted in the receiving system, the receiving system receives andloads the CAS software from the memory card so as to perform theauthentication process. In this example, the CAS software is read outfrom the memory card and stored in the first memory 4012 of thereceiving system. Thereafter, the CAS software is operated in thereceiving system as an application program. According to an embodimentof the present invention, the CAS software is mounted on (or stored) ina middleware platform and, then executed. A Java middleware will begiven as an example of the middleware included in the present invention.Herein, the CAS software should at least include information requiredfor the authentication process and also information required for thedescrambling process.

Therefore, the authentication unit 4008 performs authenticationprocesses between the transmitting system and the receiving system andalso between the receiving system and the memory card. At this point, asdescribed above, the memory card should be entitled to receive thecorresponding data and should include information on a normal receivingsystem that can be authenticated. For example, information on thereceiving system may include a unique number, such as a standardizedserial number of the corresponding receiving system. Accordingly, theauthentication unit 4008 compares the standardized serial numberincluded in the memory card with the unique information of the receivingsystem, thereby performing the authentication process between thereceiving system and the memory card.

If the CAS software is first executed in the Java middleware base, thenthe authentication between the receiving system and the memory card isperformed. For example, when the unique number of the receiving systemstored in the memory card conforms to the unique number of the receivingsystem read from the system manager 4015, then the memory card isverified and determined to be a normal memory card that may be used inthe receiving system. At this point, the CAS software may either beinstalled in the first memory 4012 upon the shipping of the presentinvention, or be downloaded to the first memory 4012 from thetransmitting system or the module or memory card, as described above.Herein, the descrambling function may be operated by the databroadcasting application manger 4016 as an application program.

Thereafter, the CAS software parses the EMM/ECM packets outputted fromthe demultiplexer 4003, so as to verify whether the receiving system isentitled to receive the corresponding data, thereby obtaining theinformation required for descrambling (i.e., the CW) and providing theobtained CW to the descramblers 4004 and 4007. More specifically, theCAS software operating in the Java middleware platform first reads outthe unique (or serial) number of the receiving system from thecorresponding receiving system and compares it with the unique number ofthe receiving system transmitted through the EMM, thereby verifyingwhether the receiving system is entitled to receive the correspondingdata. Once the receiving entitlement of the receiving system isverified, the corresponding broadcasting service information transmittedto the ECM and the entitlement of receiving the correspondingbroadcasting service are used to verify whether the receiving system isentitled to receive the corresponding broadcasting service. Once thereceiving system is verified to be entitled to receive the correspondingbroadcasting service, the authentication key transmitted to the EMM isused to decode (or decipher) the encoded CW, which is transmitted to theECM, thereby transmitting the decoded CW to the descramblers 4004 and4007. Each of the descramblers 4004 and 4007 uses the CW to descramblethe broadcasting service.

Meanwhile, the CAS software stored in the memory card may be expanded inaccordance with the paid service which the broadcast station is toprovide. Additionally, the CAS software may also include otheradditional information other than the information associated with theauthentication and descrambling. Furthermore, the receiving system maydownload the CAS software from the transmitting system so as to upgrade(or update) the CAS software originally stored in the memory card. Asdescribed above, regardless of the type of broadcast receiving system,as long as an external memory interface is provided, the presentinvention may embody a CAS system that can meet the requirements of alltypes of memory card that may be detachably fixed to the receivingsystem. Thus, the present invention may realize maximum performance ofthe receiving system with minimum fabrication cost, wherein thereceiving system may receive paid broadcasting contents such asbroadcast programs, thereby acknowledging and regarding the variety ofthe receiving system. Moreover, since only the minimum applicationprogram interface is required to be embodied in the embodiment of thepresent invention, the fabrication cost may be minimized, therebyeliminating the manufacturer's dependence on CAS manufacturers.Accordingly, fabrication costs of CAS equipments and management systemsmay also be minimized.

Meanwhile, the descramblers 4004 and 4007 may be included in the moduleeither in the form of hardware or in the form of software. In this case,the scrambled data that being received are descrambled by the module andthen demodulated. Also, if the scrambled data that are being receivedare stored in the third memory 4018, the received data may bedescrambled and then stored, or stored in the memory at the point ofbeing received and then descrambled later on prior to being played (orreproduced) Thereafter, in case scramble/descramble algorithms areprovided in the storage controller 4017, the storage controller 4017scrambles the data that are being received once again and then storesthe re-scrambled data to the third memory 4018.

In yet another example, the descrambled broadcasting contents(transmission of which being restricted) are transmitted through thebroadcasting network. Also, information associated with theauthentication and descrambling of data in order to disable thereceiving restrictions of the corresponding data are transmitted and/orreceived through the telecommunications module 4019. Thus, the receivingsystem is able to perform reciprocal (or two-way) communication. Thereceiving system may either transmit data to the telecommunicationmodule within the transmitting system or be provided with the data fromthe telecommunication module within the transmitting system. Herein, thedata correspond to broadcasting data that are desired to be transmittedto or from the transmitting system, and also unique information (i.e.,identification information) such as a serial number of the receivingsystem or MAC address.

The telecommunication module 4019 included in the receiving systemprovides a protocol required for performing reciprocal (or two-way)communication between the receiving system, which does not support thereciprocal communication function, and the telecommunication moduleincluded in the transmitting system. Furthermore, the receiving systemconfigures a protocol data unit (PDU) using a tag-length-value (TLV)coding method including the data that are to be transmitted and theunique information (or ID information) Herein, the tag field includesindexing of the corresponding PDU. The length field includes the lengthof the value field. And, the value field includes the actual data thatare to be transmitted and the unique number (e.g., identificationnumber) of the receiving system.

The receiving system may configure a platform that is equipped with theJava platform and that is operated after downloading the Javaapplication of the transmitting system to the receiving system throughthe network. In this case, a structure of downloading the PDU includingthe tag field arbitrarily defined by the transmitting system from astorage means included in the receiving system and then transmitting thedownloaded PDU to the telecommunication module 4019 may also beconfigured. Also, the PDU may be configured in the Java application ofthe receiving system and then outputted to the telecommunication module4019. The PDU may also be configured by transmitting the tag value, theactual data that are to be transmitted, the unique information of thecorresponding receiving system from the Java application and byperforming the TLV coding process in the receiving system. Thisstructure is advantageous in that the firmware of the receiving systemis not required to be changed even if the data (or application) desiredby the transmitting system is added.

The telecommunication module within the transmitting system eithertransmits the PDU received from the receiving system through a wirelessdata network or configures the data received through the network into aPDU which is transmitted to the host. At this point, when configuringthe PDU that is to be transmitted to the host, the telecommunicationmodule within the transmitting end may include unique information (e.g.,IP address) of the transmitting system which is located in a remotelocation. Additionally, in receiving and transmitting data through thewireless data network, the receiving system may be provided with acommon interface, and also provided with a WAP, CDMA 1x EV-DO, which canbe connected through a mobile telecommunication base station, such asCDMA and GSM, and also provided with a wireless LAN, mobile internet,WiBro, WiMax, which can be connected through an access point. Theabove-described receiving system corresponds to the system that is notequipped with a telecommunication function. However, a receiving systemequipped with telecommunication function does not require thetelecommunication module 4019.

The broadcasting data being transmitted and received through theabove-described wireless data network may include data required forperforming the function of limiting data reception. Meanwhile, thedemultiplexer 4003 receives either the real-time data outputted from thedemodulating unit 4002 or the data read from the third memory 4018,thereby performing demultiplexing. In this embodiment of the presentinvention, the demultiplexer 4003 performs demultiplexing on theenhanced data packet. Similar process steps have already been describedearlier in the description of the present invention. Therefore, adetailed of the process of demultiplexing the enhanced data will beomitted for simplicity.

The first descrambler 4004 receives the demultiplexed signals from thedemultiplexer 4003 and then descrambles the received signals. At thispoint, the first descrambler 4004 may receive the authentication resultreceived from the authentication unit 4008 and other data required forthe descrambling process, so as to perform the descrambling process. Theaudio decoder 4005 and the video decoder 4006 receive the signalsdescrambled by the first descrambler 4004, which are then decoded andoutputted. Alternatively, if the first descrambler 4004 did not performthe descrambling process, then the audio decoder 4005 and the videodecoder 4006 directly decode and output the received signals. In thiscase, the decoded signals are received and then descrambled by thesecond descrambler 4007 and processed accordingly.

As described above, the DTV transmitting system and receiving system andmethod of processing broadcast data according to the present inventionhave the following advantages. More specifically, the present inventionis highly protected against (or resistant to) any error that may occurwhen transmitting supplemental data through a channel. And, the presentinvention is also highly compatible to the conventional receivingsystem. Moreover, the present invention may also receive thesupplemental data without any error even in channels having severe ghosteffect and noise.

Additionally, by performing an error correction decoding process and arow permutation process on the enhanced data, and by performing an errordetection encoding process when required, robustness is provided to theenhanced data, thereby enabling the enhanced data to respond adequatelyand strongly against the fast and frequent change in channels.Furthermore, the present invention is even more effective when appliedto mobile and portable receivers, which are also liable to a frequentchange in channel and which require protection (or resistance) againstintense noise.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A digital television (DTV) transmitting system for processingbroadcast data, the DTV transmitting system comprising: a randomizerrandomizing enhanced data; a Reed-Solomon (RS) frame encoder generatingan RS frame by RS encoding an RS frame payload with an RS code of(187+P, 187) and Cyclic Redundancy Check (CRC)-encoding the RS-encodedRS frame payload, wherein the RS frame comprises (187×N) bytes includingthe randomized enhanced data, P bytes of RS parity data added at abottom of each column of the (187×N) bytes and 2 bytes of CRC data addedat a right end of each row of the ((187+P)×N) bytes, wherein P and N aregreater than 1; a block processor encoding the data in the RS frame at acoding rate of 1/N1, wherein N1 is an integer greater than 1; a groupformatting unit mapping a portion of the data encoded at the coding rateof 1/N1 into a data group, wherein the group formatting unit adds knowndata sequences, main data place holders, moving picture experts group(MPEG) header place holders, and RS parity data place holders to thedata group, and wherein at least two of the known data sequences arespaced 16 segments apart; a deinterleaver deinterleaving data of thedata group; a packet formatter removing the main data place holders andthe RS parity data place holders in the deinterleaved data group andreplacing the MPEG header place holders in the deinterleaved data groupwith MPEG headers having a packet identifier, in order to outputenhanced data packets; and a trellis encoding unit trellis encoding dataof the enhanced data packets, the trellis encoding unit including atleast one memory initialized at each start of the known data sequences.2. The DTV transmitting system of claim 1, further comprising: amultiplexer multiplexing the enhanced data packets output from thepacket formatter with main data packets including main data.
 3. The DTVtransmitting system of claim 2, further comprising: an RS encoder addingRS parity data to the multiplexed data packets.
 4. The DTV transmittingsystem of claim 3, further comprising: an interleaver interleaving dataof the multiplexed data packets including the RS parity data.
 5. Amethod of processing broadcast data in a digital television (DTV)transmitting system, the method comprising: randomizing, by arandomizer, enhanced data; generating, by a Reed-Solomon (RS) frameencoder, an RS frame by RS encoding an RS frame payload column with anRS code of (187+P, 187) and Cyclic Redundancy Check (CRC)-encoding theRS-encoded RS frame payload, wherein the RS frame comprises (187×N)bytes including the randomized enhanced data, P bytes of RS parity dataadded at a bottom of each column of the (187×N) bytes and 2 bytes of CRCdata added at a right end of each row of the ((187+P)×N) bytes, whereinP and N are greater than 1; encoding the data in the RS frame at acoding rate of 1/N1, wherein N1 is an integer greater than 1; mapping aportion of the data encoded at the coding rate of 1/N1 into a datagroup, wherein the data group further includes known data sequences,main data place holders, moving picture experts group (MPEG) headerplace holders, and RS parity data place holders, and wherein at leasttwo of the known data sequences are spaced 16 segments apart;deinterleaving data of the data group; removing, by a packet formatter,the main data place holders and the RS parity data place holders in thedeinterleaved data group and replacing the MPEG header place holders inthe deinterleaved data group with MPEG headers having a packetidentifier, in order to output enhanced data packets; and trellisencoding, by a trellis encoding unit, data of the enhanced data packets,wherein at least one memory included in the trellis encoding unit isinitialized at each start of the known data sequences.
 6. The method ofclaim 5, further comprising: multiplexing the enhanced data packets fromthe packet formatter with main data packets including main data.
 7. Themethod of claim 6, further comprising: adding RS parity data to themultiplexed data packets.
 8. The method of claim 7, further comprising:interleaving data of the multiplexed data packets including the RSparity data.